TThe first reading of the Champions League quarterfinals for the 2025-26 season has already been decided. It’s math, not soccer. Based on the Elo system (a model taken from chess that measures the actual “strength” of a team based on its results), it is possible to estimate the chances of qualification in each draw. The result was four clear favorites, but none with a completely clear path forward.
The starting point for the entire model is the ClubElo ranking. This is not a traditional ranking. We count performance, not titles or accumulated points. It is used by teams, national teams, and even analytical institutions because it can convert the difference in level into a probability of winning. In soccer, for example, FIFA has been using a modified version of the Elo system (called the “SUM” algorithm) for its world rankings since August 2018.
In each match, the score a team can earn changes depending on the opponent, result, and situation. Winning against a big team gives you much more than winning against a small team, and losing to a small team gives you more penalties. That’s why Elo has a pretty accurate picture of each club’s current level of competition.
Based on this, the first thing to do is to convert this level of difference into a probability of matching. In other words, if one team has more Elo than another, that team is the favorite to win, but not in an absolute sense. The system converts this into a probability of winning. This gives you a realistic estimate that there is always room for improvement, even for bad teams.
our predictive adaptation
From there, MARCA adapted the model to the actual knockout rounds, based on the rankings at the time the brackets were established (March 18th). First, it incorporates the home field element, which is important in the Champions League. Playing at home is not the same as playing away. The model incorporates this as a small “bonus” to the home team, giving them an average advantage of +65 Elo points. In practical terms, this means that many ties are balanced. This means that a team may be an underdog overall, but still a favorite in their own stadium. This explains why some ties seem so close when analyzed match by match.
The next step is to adapt these probabilities to what actually happens in soccer. It’s not all about wins and losses; there are also draws. To do this, an average draw rate (approximately 27%) based on historical Champions League data is introduced, which allows the probability of each match to be divided into three possible outcomes. This is an important detail because two-legged ties put a lot of weight on the draw.
Finally, we considered all possible scenarios back and forth, including overtime and penalties (assuming 50-50), to obtain the final probability of qualification. The final result is the sum of the scenarios, not the closed prediction. In other words, it’s a percentage that reflects how many times each team would win if that draw were to occur many times. In short, it’s a way to translate each team’s “strength” into actual odds of making it to the semi-finals.
Real Madrid vs. Bayern Munich: Bayern side maintains advantage
Although not definitive, the balance is tipped more between Bayern Munich and Real Madrid. The German side have a 55.5% chance of qualifying, compared to Madrid’s 44.5%. The key lies in the return match in Munich. This model reflects that the German team has a better margin in the stadium, which makes up for the parity in the first leg.
Madrid have a slight advantage in the first leg at the Bernabéu (38.8% vs. 34.2%), but the model is more emphasized in the second leg. Bayern wins 47.5% compared to Madrid’s only 25.5%. This imbalance in the second leg resulted in a draw in Bayern’s favor. Even so, the overall gap is still small, and although there are contenders for the win, the scores are tied at the halfway point without an advantage.
PSG vs Liverpool: coin toss in slight favor for France
Due to this process, the most even match will be Paris Saint-Germain vs. Liverpool. PSG have a 54% chance of qualifying, but this is a minimal advantage explained by the situation rather than a clear advantage. Both teams are favorites to win if they play at home, so this is a very delicate draw. One goal can more or less completely change the scenario.
In the first leg in Paris, France have a win probability of 46.4% compared to Liverpool’s 26.6% (remember we set the average draw at 27%), but in the second leg at Anfield the scenario is reversed, with England at 40.1% and PSG at 32.9%. From a probability perspective, this is the closest combination to a coin toss.
Barcelona vs. Atlético Madrid: Blaugrana’s advantage even in the Metropolitano
The difference became even clearer in the Spain match between Barcelona and Atletico Madrid. Barça have a 62.1% chance of qualifying and, most importantly, according to the model, are favorites to win both games, even in the Metropolitano. In the first leg at the Camp Nou, the Blaugrana had a winning probability of 52.3% compared to Atlético’s 20.7%, and in the second leg at the Metropolitano they are still favorites: 39.8% against 33.2%.
This double condition is what gives rise to the final probability. It depends not only on home field factors, but on persistent differences in “strength”. Still, given the gravity of the draw and the close scenario, Atlético are left with realistic options.
Sporting vs Arsenal: the most unbalanced duel
Finally, the most unbalanced matchup is Arsenal vs. Sporting CP. The English side have a 73.1% chance of qualifying and are favorites to win the first leg in Lisbon (49.6% to 23.4%). In the second leg in London, the difference is even greater, with a 59.7% chance of winning compared to just 13.3% for Sporting.
These numbers reflect large gaps in levels and explain why this is the collision with the lowest uncertainty of all collisions.
In other words, the Elo system draws two very open draws in the quarter-finals (PSG vs. Liverpool, Bayern vs. Madrid), one with the clear favorites (Barça vs. Atlético) and one with the clear favorite (Arsenal vs. Sporting). “Strength” shows the way… But as always in the Champions League, the reality is that there is still much to be said.
