ByAlex BysouthBBC Sport Senior JournalistPublished11 minutes agoCommentsIt's the business end of the Champions League, where heroes are made and Ballon d'Or winners forged. But which players will prove most pivotal to their team's success?
This week, with Paris St-Germain facing Bayern Munich and Atletico Madrid hosting Arsenal in the semi-finals, we're looking at those key cogs among the clubs battling for Europe‘s grandest prize.
This is not a list merely of the biggest stars - although many of them feature - but those players whose presence could be vital to their team reaching the final in Budapest.
You can have your say at the bottom of the page too.
Matteo Ruggeri has started 11 of Atletico Madrid's 14 games in this season's Champions League and, with Diego Simeone's side up against an Arsenal outfit who beat them 4-0 earlier in the competition, it figures that the left-back will be an important presence in the semi-finals.
The La Liga outfit have used a low block more times than anyone else - 458 times in 14 games - and 23-year-old Italian Ruggeri has played a key role in helping Atletico preserve leads.
He has made more interceptions than any of his team-mates and is third overall in the competition this season with 20, while no Atletico player has won more tackles than the battle-hardened Ruggeri, who finished the return leg against Barcelona with blood seeping from his forehead.
Ruggeri was tasked with trying to keep Lamine Yamal quiet during the quarter-finals, and his job this time might be trying to stifle Arsenal's Bukayo Saka.
The England winger missed more than a month with an Achilles problem, including both legs of the quarter-final win over Sporting, but, given the Gunners struggled to break down the Lisbon outfit in his absence - and taking into account Atletico’s penchant for a low block - Saka may prove key to unlocking their defence.
Opta has Arsenal down as marginal favourites to win the Champions League this season, ahead of Bayern Munich, and Mikel Arteta's side have been a different beast with Saka in the line-up, averaging 2.6 goals and 2.3 expected goals (xG) per game in the eight matches the 24-year-old has played compared to only 1.5 goals and 1.8 xG on average in the four he missed.
Legendary Brazilian right-back Cafu recently claimed Achraf Hakimi is the best in the world in that position, and it's hard to argue given his contributions to Paris St-Germain in the Champions League this campaign.
The Parisiens boast a potent threat on both flanks with Nuno Mendes offering similar output from left-back, but we'll go with Hakimi as being more important to their attempt at retaining the European crown given Lucas Hernandez has shared the left-back load with Mendes this term.
Bayer Leverkusen's Alejandro Grimaldo is the only defender to edge Moroccan Hakimi for goal contributions in this season's competition, making five assists and scoring once.
But Hakimi (7.5 on average per game) and Mendes (7.6) are a long way clear when it comes to defenders who have been involved in the most attacking moves per game.
This could equally have been Aleksandar Pavlovic, who has completed more passes than any of his Bayern Munich team-mates in the Champions League this season and was superb in the win over Real Madrid, but I've gone with Joshua Kimmich for his importance to a side who rightfully tend to get most plaudits for their attack.
The 31-year-old midfielder has been key to unleashing that ruthless frontline, with his 19 defensive line-breaking passes the most in Europe's showpiece competition. He is the only Bayern player in double figures.
Only irrepressible PSG midfielder Vitinha (345) has made more successful passes into the final third than Kimmich (301) and Pavlovic (285), but Kimmich has got the ball into the penalty box more than any other player this season.
Ousmane Dembele racked up eight goals and six assists in Europe during his Ballon d'Or-winning campaign last season, the record for a PSG player in a season as they clinched the Champions League for the first time.
Yet at the semi-final stage this time around Khvicha Kvaratskhelia is only one shy of that, with his eight goals and five assists putting the Parisiens on course to defend their crown.
The Georgia winger is as effective as he is mesmerising, taunting opposition with a languid but unstoppable dribbling style, socks at half mast on his calves, defenders clawing at the scorched turf left behind him. He's deadly - and Bayern know it.