Champions League semi-finals: Breaking down the strengths and weaknesses of all four contenders

New York Times

28-04-2025

From 36 clubs at the start of the season, just four remain.
After four quarter-finals filled with tension, it is Inter and Barcelona, and Arsenal and Paris Saint-Germain who face off in two blockbuster semi-final ties.
While the remaining quartet still represent some of Europe's heavyweight clubs, there is a refreshing narrative that is guaranteed to occur this year. Arsenal and PSG are still looking to win the competition for the first time in their history while Barcelona and Inter have not lifted the trophy for a decade or more. In a period dominated by Real Madrid and other English powerhouses, a new chapter is imminent.
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As things stand, Arsenal edge it as the favourites to lift the trophy with a 28.7 per cent chance of victory per Opta's Supercomputer. In truth, the margins are paper-thin between the final four — and you could make a strong case for any of the remaining clubs to go all the way.
Where might each tie be won and lost? Allow The Athletic to walk you through the tactical wrinkles for each side, with the added inclusion of a few data nuggets to whet the appetite for this week's matches.
Forget the Premier League, Arsenal are on a rampage in Europe.
Mikel Arteta's men were good value for their victory against holders Real Madrid after progressing to their first semi-final since 2009 — showing different sides to their game in and out of possession across both legs.
For all that they have come unstuck against deep defensive blocks in recent seasons, Arsenal's attacking style is arguably more suited to the Champions League as they face up to teams more willing to go toe-to-toe with them.
With greater space for their wingers to stretch their legs, Arteta's side have doubled down on width when going forward in Europe. Of the remaining semi-finalists, Arsenal's 24 per cent share of attacking touches through the middle of the pitch is the lowest.
Bukayo Saka's return to fitness and form has been unanimously welcomed by Arsenal fans, with the 23-year-old having a crucial impact in Arsenal's victory over Madrid. His two fouls drawn allowed Declan Rice to steal the headlines with his subsequent free-kick strikes, with a dead-eyed dinked finish at the Bernabeu capping off a pair of memorable performances.
The game in Spain took a different form to the first leg at the Emirates. For long periods, Arsenal set up in their typical 4-4-2 out of possession at the Bernabeu — staying compact to force Madrid into wide areas and rarely through the centre of the pitch.
However, there were plenty of occasions when this defensive shape dropped even deeper.
Such was the strong organisation that Arteta's side showed out of possession that you could map different sequences dropping into a back five, a back six, a back seven, and even a back eight across the duration of their second-leg victory — with Rice or Thomas Partey dropping between the centre-backs, or Saka and Gabriel Martinelli tracking back to support their respective full-back.
While you would not expect Arsenal to perform in the same way across the entirety of their semi-final tie against PSG, there may be occasions when similar penalty-box defending will be required.
Given the fluid rotations of Luis Enrique's forward line, Arsenal will need to ensure that they do not break their structure too often across both legs. Fortunately, Arteta's side thrive out of possession, boasting the second-strongest defensive record across Europe's top five leagues when looking at their 0.83 expected goals conceded per 90 minutes this season.
Add in the fact that Arsenal kept a clean sheet in their 2-0 victory over PSG during the competition's league phase in October, and there is reason to be quietly confident of more memorable nights in north London and Paris.
A second successive Champions League semi-final is not to be underestimated for PSG, particularly given the context within which Luis Enrique has achieved the feat this season.
A Kylian Mbappe-less PSG is one that is far more cohesive, co-ordinated, and coherent than recent years, and it is clear that this is the closest iteration to Enrique's ideals — both in and out of possession — since he arrived in the French capital.
A 3-1 first-leg lead over Aston Villa should have made for a straightforward second-leg at Villa Park but Unai Emery's men gave PSG a scare with some aggressive, direct attacks through the heart of their defence.
'Villa never managed to equalise the tie but for 10 minutes, we wondered whether we could keep the ball, if we could get the ball out of midfield or play long,' Luis Enrique said after the game.
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'I don't think this team has been so dominated by another team in that way, but this opponent has to take risks because they were going out of the competition. They attacked with great intensity and we were playing in front of a great crowd too.'
Many clubs can get swept up in the atmosphere of a Champions League night under the lights but PSG stood firm with some help from goalkeeper Gianluigi Donnarumma — and were deserving winners across the two legs.
Luis Enrique will be less pleased about PSG's out-of-possession performance on that Tuesday evening at Villa Park, particularly when considering it has been one of the strongest parts of their game this season. A co-ordinated high-pressing approach has helped to force opponents to go long when building up as PSG look to regain the ball as quickly as possible and dictate the tempo of the game.
It feels disingenuous to discuss PSG's defensive approach before acknowledging their incredible technical quality going forward. They might have had a slower start than they would have liked in this year's Champions League but there is little doubt that they have clicked into gear at the perfect time.
Step off them and they have the technical quality of Joao Neves, Vitinha and Fabian Ruiz to pop the ball around you, with any of them dropping outside of the opposition block to kick-start PSG's progression through the thirds.
Get tight to them and they have the individual quality to make some of Europe's best look rather ordinary. For context, PSG's 27.9 take-ons per 90 is more than any other side in the Champions League this season, with one-v-one specialists across the forward line.
It was less frequent at Villa Park but any one of Ousmane Dembele, Bradley Barcola, Desire Doue or Khvicha Kvaratskhelia will frequently rotate across the forward line and pop up in different positions across the pitch.
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Throw in the running power of full-backs Nuno Mendes and Achraf Hakimi — both of whom scored in their quarter-final second leg — to support attacks, and it is often a case of picking your poison when PSG throw bodies forward.
Mendes' goal was a perfect example of the razor-sharp threat that Enrique's side possesses. Third-man running, one-touch play and maximum width across the pitch make for a devastating combination.
It is fair to say that PSG were a little undercooked in their October game against Arsenal but Luis Enrique's men have hit top gear in the months that followed. With a(nother) Ligue 1 title sewn up and a treble-winning season still on the cards, the momentum is with PSG as they look to lift the Champions League trophy for the first time.
A 3-1 second-leg defeat by Borussia Dortmund was an anomalous result for Barcelona.
Their 24-game unbeaten run had ended but a four-goal buffer from the first leg meant that Hansi Flick's side were never likely to be at full tilt at Westfalenstadion, managing the tie more so than the game itself.
As well as their three strikes, Dortmund had the ball in the back of the net twice more after Pascal Gross and Julian Brandt made deep runs behind Barcelona's defensive line to race through on goal.
Both efforts were chalked off for offside but the events were a microcosm of Barcelona's season under Flick with a brave high line.
The numbers to support this are staggering. Barcelona have drawn opponents offside on 68 occasions in the Champions League this season, which is comfortably the most of any team to have made it into the knockout phase. For context, Aston Villa are the second-highest on the list with 34 — exactly half the number with the same number of games played.
With an average defensive line height of 33.7 metres — the highest of any side to make it to the knockout phase — Barcelona's choreographed approach out of possession has been highly refined under Flick.
That being said, there are signs that such an approach is fallible. With Ronald Araujo coming into Flick's defence against Dortmund, Barcelona fans must still wince when watching the bravery that is required to play such a high line.
That approach will gain increased focus against Inter's attacking duo of Lautaro Martinez and Marcus Thuram. While neither has blistering pace to run in behind, their neat combination play is enough to worry any defence in European football.
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Of course, Barcelona's strengths far outweigh any weaknesses under Flick as they push for another historic treble. Going forward, the versatility that they offer makes them perfectly suited to knockout football — resembling Luis de la Fuente's Spain national team during their winning Euro 2024 campaign.
On the one hand, Flick's side are one of the teams most likely to play nine-plus passes per sequence in the competition, regularly circulating possession with the technical quality of Pedri, Frenkie De Jong, and (earlier in the competition) Marc Casado.
However, do not be fooled into thinking Barcelona simply pass teams into submission. The pacy threat and tireless running of Lamine Yamal and Raphinha means that Flick's side can punish you in transitional moments.
Eight of their goals in the Champions League this season have come from direct attacks, the most of any side in the competition. They might not employ it as frequently as others — for example, PSG boast double the volume of direct attacks this year — but when they do regain possession, Barcelona can pierce through opposition defences in the blink of an eye.
Raphinha has had a career-best season in Spain with 12 Champions League goals to sit alongside his 15 La Liga strikes — but Yamal is undoubtedly the jewel in Barcelona's crown.
Many superlatives have already been attached to Yamal's name but the teenager's unpredictability is one of his strongest traits in his fledgling career. When mapping his progressive carries in La Liga this season, you can see below that he is equally likely to cut inside onto his stronger left foot, drive outside to his right, or direct his runs straight towards goal.
Whether Yamal will have the same joy against Inter's defensive back five is another story. Simone Inzaghi's side are one of the toughest teams in Europe to break down and will often double up in wide areas against opposition wingers — whether it is a supporting centre-back or midfielder to drop in and help their respective wing-back out of possession.
For all of the incredible talent on display for both sides, keep an eye on the flanks across both ties.
Inter might be viewed as underdogs but no remaining team has reached a Champions League final more recently.
The core of that side is still intact, with eight of the starters from the 2023 final — a narrow 1-0 defeat by Manchester City — still at the club. That continuity has allowed Inzaghi to mould the most tactically distinct team left in the competition.
While the other semi-finalists are broadly defined by high pressing and front-footed play, Inter favour a more measured, controlled approach. Of the teams to reach the last 16, only Club Brugge pressed less intensely, as shown on the PPDA graphic below.
Instead, Inter are comfortable sitting deep, holding their disciplined 3-5-2 shape, and building slowly from the back. Their direct speed — a measure of how quickly a team progresses the ball upfield — is slower than every Champions League side except for Pep Guardiola's Manchester City.
This restrained approach complements their out-of-possession game. Like classic Italian sides of the past, they are comfortable defending without the ball — no team has conceded fewer than their five goals in this season's competition. Inzaghi often speaks of Inter's willingness to do the hard yards out of possession; ahead of their quarter-final second leg against Bayern Munich, he predicted the match would contain 'moments where we'll have to suffer'.
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That proved true across both legs as Inter conceded the bulk of possession to Vincent Kompany's side. While they rode their luck at times, Inter's methodical build-up means they are rarely caught out of shape when they forfeit the ball. They have conceded just 0.18 xG from fast breaks and their xG per shot against is the lowest in the competition.
Yet their disciplined approach should not be mistaken for being unadventurous. Inter are one of the most fluid sides in Europe, with positional rotations a key feature of their possession play.
Nicolo Barella's touch map in this season's competition reflects that fluidity — nominally a central midfielder, he has popped up on both wings, in deeper defensive zones, and in the final third behind the two strikers. Inzaghi gives his players the licence to rotate freely, making Inter unpredictable in attack and capable of creating overloads across the pitch.
Another strength of Inzaghi's system is the blossoming partnership it enables up top between Martinez and Thuram. A two-man strike force is increasingly rare in modern football, but it has given Inter a unique edge.
Before facing RB Leipzig earlier in the competition, Inzaghi spoke of the importance of 'keeping our shape, and knowing when to pick our moments'. Inter's first goal away at Bayern was a textbook example — and the telepathic understanding between the two strikers was pivotal.
After launching a quick break, Thuram played an intelligent backheel from the middle of the box into the path of Martinez, who finished with the outside of his boot, in what was a real contender for goal of the competition.
INTER ARE AHEAD, AND WHAT A GOAL 🤧
Beautiful build up play finds Thuram who brilliantly back-heels into the path of Lautaro Martinez, and his outside of the foot finish finds the back of the net ⚽️
📺 @tntsports & @discoveryplusUK pic.twitter.com/ZU0IuJwdQ0
— Football on TNT Sports (@footballontnt) April 8, 2025
Against Barcelona, Inter will again likely be limited to fleeting moments on the ball. But with their defensive discipline, tactical flexibility, and ability to strike with precision, they remain more than capable of posing a serious threat.
When Inter faced Barcelona in 2022, Inzaghi said: 'It is a very delicate match, where we have to show our teeth.'
Expect the same again.
(Top photos: Bukayo Saka, left, and Lautaro Martinez; Getty Images)