It might seem like there are clear favorites in each Champions League quarterfinal matchup, but based on the betting odds, there’s only about a 1-in-5 chance that Real Madrid, Bayern Munich, Paris Saint-Germain and Barcelona all advance.
That’s because a lot can happen across 180 minutes of knockout soccer.
Optimal tactics, systems, strategies, roster quality, talent depth are the things that win you league titles. But over just two matches, individual performances and stylistic dynamics matter more than anything else.
Two underwhelming matches from your star winger, and suddenly you’re sitting at home. A blinder from your backup fullback? Here’s your ticket to the semifinals.
So, ahead of the first legs of the four remaining matchups kicking off Tuesday and Wednesday, let’s take a look at the players, people and philosophies that might have an outsize effect on who punches through to the semifinals.
Here are your eight X factors for the UEFA Champions League quarterfinalists:
Arsenal (vs. Real Madrid): Martin Ødegaard
Arsenal’s quarterfinal matchup is Real Madrid, a team for which the players have changed some but the performances haven’t over the past five years. They still have an incredible amount of attacking talent that frequently underperforms but also has an uncanny ability to elevate in the highest-leverage moments of matches.
Defensively, it’s kind of just vibes, hoping players make plays while trusting in Thibaut Courtois. Among the remaining teams, only Aston Villa allows a higher opposition pass-completion rate and presses less aggressively (as measured by passes allowed per defensive action) than Madrid. And only Villa and Dortmund allow more shots per game, goals per game and expected goals per game.
Madrid, in particular, seem to struggle with players who put unique stress on their defensive structure. The structure isn’t too strong to begin with, so any time an opposition player can pick up possession between the lines or in the half-spaces between the fullback and center back, it can lead to chaos. A cascade of missed assignments and wrong decisions creates space in all the wrong places.
The player most capable of exploiting that: Arsenal’s captain, Martin Ødegaard.
Now, Ødegaard is having a down year in just about every way. He’s scoring fewer goals, registering fewer assists, taking fewer shots, creating fewer chances, generating fewer touches inside the box and making fewer tackles and interceptions than he did last season. But that’s “down” only when compared to level he was at last year as a top 10 player in the world. Plus, he has been injured, as have so many of his teammates.
With his rightside running mate, Bukayo Saka, back in the fold, could we see the former Madrid player return to the levels we saw a year ago? If Arsenal are going to generate any kind of consistent attacking threat beyond set pieces against Madrid, Ødegaard will need to be at the center of it.
Real Madrid (vs. Arsenal): Vinícius Júnior
Although so much of the focus has been on Kylian Mbappé‘s fits and starts with Madrid, Vinícius Júnior has been the bigger disappointment so far this season.
His top-line numbers look fine compared to last season, but that’s only because he really didn’t play all that much in LaLiga last year. It’s early April, and Vini has already played nearly the same number of domestic minutes as he did last season.
On a per-minute basis, though, he has played well below the Ballon d’Or level he claimed to be at in 2023-24. He’s taking fewer shots than last season — and from much worse locations. That has added up to a large drop in non-penalty goal scoring: 0.68 last year, down to 0.44.
However, he’s still carrying the ball into the penalty area as much as he ever has, and he’s beating more defenders off the dribble than he did last season. That’s all despite attempting fewer take-ons and carries than he did a year ago.
Arsenal are the best defensive team in the world, in this writer’s opinion. They allow fewer goals than any remaining team in the competition despite playing in the toughest league among Europe’s big five leagues.
Week after week, the Gunners control possession and then when they lose it, they clog up the middle of the field, encourage their opponents to try to beat them on the wings and then eat them alive. Madrid won’t have a press or a sophisticated possession system to stress Arsenal’s defense. Instead, they’ll need to get the ball wide to Vini and ask him to find a way to break it apart.
Bayern Munich (vs. Inter Milan): Vincent Kompany
It still really doesn’t seem like Vincent Kompany has been tested by a truly high-stakes matchup yet since he took over as Bayern Munich’s manager before the start of this season.
The scoreless draw with Bayer Leverkusen a month ago, combined with the struggles against Celtic in the round before the round of 16, seemed to portend future issues against better competition in Europe. Then … Leverkusen completely imploded in the first leg of their round of 16 matchup, and we really didn’t learn much about Kompany along the way.
We still might not learn much against Inter Milan because Bayern have a significantly more talented roster. But Inter’s Simone Inzaghi is one of the best managers in the world and has found a way to build a near-elite team around a midfield that includes two 30-something former attacking midfielders and a 5-foot-7-and-change Nicolò Barella.
Inter are better than they should be — given how old the team is and how much money they spend compared to the powerhouses across the continent — and Inzaghi deserves a large share of that credit. He uses subs as well as anyone, and his team is one of the more tactically flexible sides at the highest level.
Kompany is the, um, exact opposite of that. He has succeeded in the two phases of his career in which he has had more talent and resources than most if not all of his domestic competition. His teams can just keep the ball forever, move it slowly and then eventually create chances because of a sheer talent advantage.
But once the talent advantage starts to even out, you need more than “possession” to consistently win games. We saw it fall apart for Kompany in the Premier League last season with Burnley, and it really should start to get stress-tested against Inter.
With injuries to Jamal Musiala, Kingsley Coman, Alphonso Davies, Dayot Upamecano and Manuel Neuer, can Kompany come up with the right game plan with what’s left of his roster?
Inter Milan (vs. Bayern Munich): Alessandro Bastoni
Take a look at this heat map:
Give us your best guess: What position does the person who produced this play? Maybe left wing on a more traditional, defend-and-counter side? Or perhaps a left-sided central midfielder — either an eight in a midfield three or the left-sided holding midfielder in a two? It could even just be a fullback — pinching infield with the ball sometimes and occasionally getting forward?
Wrong, wrong, wrong and wrong. This beautiful collection of touches was produced by a left-sided centerback in Inter Milan’s back three. And this isn’t just a fun little quirk. No, Alessandro Bastoni is producing plenty of value for Inter Milan with his barely traceable movements up, down and across the field.
Per Stats Perform’s expected possession value model, Bastoni has contributed 3.38 goals worth of value with his on-ball actions in open play. That’s third among all Inter players, and if we include all aspects of play, he’s first among all centerbacks in Serie A.
With all of the injuries to Bayern’s backline, Bastoni’s ability to progress the ball into dangerous areas could be vital — but so too will his ability at the other end of the field. Michael Olise leads all Bayern players in non-penalty expected goals plus expected assists this season, and he plays on the right wing — or, right inside one of the many dense spots across Bastoni’s heatmap.
Paris Saint-Germain (vs. Aston Villa): Willian Pacho
Along with Barcelona, PSG are the other big favorites to advance to the semifinals.
Although the round of 16 tie went to penalties, PSG outshot Liverpool 41 to 28 and created 4.41 expected goals to the 1.78 they conceded. Liverpool are currently 22 points ahead of Aston Villa in the Premier League — they have a plus-42 goal differential, while Villa have conceded as many goals as they’ve scored.
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FRIDAY, APRIL 11 (all times ET)
• HSV vs. Braunschweig (12:30 p.m.)
• Wolfsburg vs. RB Leipzig (2:30 p.m.)
• Valencia vs. Sevilla (3 p.m.)
• Charlotte vs. Forward Madison (7 p.m.)
SATURDAY, APRIL 12 (all times ET)
• Chelsea vs. Liverpool (WSL) (7 a.m.)
• Leverkusen vs. Union Berlin (9:30 a.m.)
• Bayern vs. Dortmund (12:30 p.m.)
• Leganes vs. Barcelona (3 p.m.)
SUNDAY, APRIL 13 (all times ET)
• Man City vs. United (WSL) (10 a.m.)
• Alaves vs. Real Madrid (10 a.m.)
• Bay FC vs. Chicago Stars (7 p.m.)
PSG are going to press high and try to bury Villa under an avalanche of chances. We know this … because it’s exactly what they did against Liverpool. Outside of one of those freakish ties where the shots just don’t go in, the only way to really see this working for Villa is if they hit PSG a bunch of times on the counter.
For as great as PSG’s midfield is, there’s really no one true defensive midfielder among the options. So, like it did in the first leg against Liverpool, the onus will likely fall on PSG’s centerbacks to make a couple plays in the open field to stifle any Villa threat. Among the pair, the much more active member is Willian Pacho.
While most counting stats don’t tell us much about centerback quality, they can tell us a lot about roles. And, well, Pacho leads all PSG players in tackles+interceptions. That’s not normal, especially for a team that tries to keep the ball pinned in the opposition third so aggressively.
If PSG win the tie without too much fuss, Pacho’s aggressive ball-winning will be a big reason why.
Aston Villa (vs. PSG): Youri Tielemans
Here’s how the pass-grading process at PFF FC works, per PFF FC:
PFF grades each event on a -2 to +2 scale with increments of 0.5, with 0 being the expected grade. For example, an unpressured pass to an open target that is completed earns a 0 grade, while a pass that breaks through a defensive line under pressure is above expectation and likely rewarded with a positive grade.
Unlike traditional data, PFF measures “performance relative to expectation” instead of just traits or measurable factors. The system looks at every play, creating a large sample size that eliminates bias and identifies undervalued players while avoiding player hype. The grading process evaluates players objectively, regardless of perceived ability.
Per PFF FC, Youri Tielemans has executed the most positively graded passes under pressure (63) in the Premier League. And based only on their domestic play, PSG are the most aggressive pressing team in Europe. They allow 8.49 passes per defensive action in (roughly) the opposition half, while the average is all the way up at 13.58.
If Tielemans can keep it up in the limited number of touches he’s likely to get against PSG, then Villa might be able to generate enough chances to make this a contest.
Barcelona (vs. Borussia Dortmund): The offside trap
FBref has advanced data for goalkeepers going back to the 2017-18 season for all of Europe’s Big Five leagues. One of the stats they track is how many times a goalkeeper has to make a defensive action outside of his penalty area. Before this season, the most were the 124 recorded by Bayern Munich‘s goalkeepers in the 2019-20 season. But now the record-holders are 2024-25 Barcelona with 125.
The big difference: Bayern played through a whole season when they set the record five years ago, while Barcelona still have two months of games left to go for this season.
The similarity, of course, is the coach: Hansi Flick. His extreme tactical approach has been an unmitigated success with Barcelona, too. Barca are the best team in LaLiga, they’re one of the most thrilling and effective attacking teams we’ve ever seen, and they’re currently the favorites to win the Champions League.
That doesn’t mean it comes without tradeoffs, though. As we saw against Benfica, Barca’s high line isn’t immune to an opposition player simply dribbling directly through it. Among the remaining teams, Barcelona allow, by far, the highest-quality shots to their opponents. In fact, only seven other teams in Europe’s “Big Five” leagues give up better chances than Barcelona’s 0.125 expected goals per shot.
The bet — and the typical outcome — is that Barcelona allow so few shots and create so many chances on the other end that the handful of backline breakdowns don’t matter. Dortmund are the biggest underdogs of any of the four matchups, and if they’re going to have any chance of pulling the upset, they’ll need that offside trap to misfire more than a couple times.
Borussia Dortmund (vs. Barcelona): Gregor Kobel
Based on the odds at ESPN Bet, the implied chances for every team to advance to the semifinals are as follows:
• Arsenal: 40%
• Real Madrid: 60%
• Bayern Munich: 56%
• Inter Milan: 44%
• PSG: 77%
• Aston Villa: 23%
• Barcelona: 79%
• Borussia Dortmund: 21%
So, if any team is going to need its goalkeeper to stand on his head, it’s Dortmund. And we saw their ‘keeper do it just a year ago and the year before that.
Per Stats Perform’s post-shot expected goals model, the average ‘keeper would’ve been expected to concede 21.41 goals from the 76 shots Gregor Kobel faced in the 22-23 and 23-24 Champions League campaigns. If we strip out the own goal, he conceded just 11.
For Dortmund to advance, or even just stay competitive in the tie, they’ll need Kobel to turn back the clock 12 months.
