Saturday's Champions League final offers one of the most fascinating tactical clashes in recent memory: Jurgen Klopp's Liverpool, with their astute, intensive, counter-pressing approach, meet the more laissez-faire style of Zinedine Zidane's Real Madrid, who concentrate upon possession play.
It has all the makings of a superb match. Here are four key questions waiting to be answered.
1. What formation will Zidane use?
The most remarkable thing about Real Madrid's Champions League record under Zidane is the sheer number of matches they have won despite appearing to be outwitted in terms of game plan. Madrid have repeatedly seemed vulnerable in a certain area, yet individual magic in the final third has saved the day.
In Kiev, however, they're up against a side boasting a comparable level of individual brilliance upfront, and therefore, it feels essential that Zidane's side are not second-best in a tactical sense. Liverpool will use their customary 4-3-3, so how will the European Cup holders respond? There are two obvious options.
The first is using the diamond midfield that has generally been Zidane's preferred system in the Champions League. Theoretically, that would see Madrid enjoy a numerical advantage in the centre of the pitch, with Isco coming into the lineup alongside Casemiro, Luka Modric and Toni Kroos. There's a danger, however, that such a narrow system will make it easier for Liverpool to press and box Madrid into the sides of the pitch when, for example, Real's full-backs have the ball.
Therefore, Zidane could use a 4-3-3 system himself. This would probably feature Karim Benzema upfront, with Cristiano Ronaldo as an inside left and Gareth Bale on the right (though Isco, Marco Asensio and Lucas Vazquez could also feature, while Ronaldo played upfront in this alignment at Bayern Munich in the semifinal). This approach would stretch play and target Liverpool's full-backs, who have been excellent this season but nevertheless can find themselves isolated.
2. Can Marcelo cope against Salah?
While capable of being a key player by pushing forward on the overlap to exploit Ronaldo's habit of narrowing the opposition right-back, sometimes Marcelo's defensive vulnerability costs his side. He was Brazil's worst performer in their infamous 7-1 World Cup semifinal loss to Germany in 2014, and statistics suggest that an increasing number of Real concessions come from his flank.
Salah's form this season has been incredible, with the Egyptian forward breaking the Premier League record for goals in a 38-game campaign with 32. But while his strikes have come from a variety of positions, it feels like he'll spend the majority of this match in a wide-right role -- especially when Madrid have possession -- waiting to pounce on the counterattack.
In Liverpool's semifinal win vs. Roma, Salah was happy to let the opposition left-back/wing-back Aleksandar Kolarov go free on the overlap, confident that he'd do more damage on the break than his opposite number. But Marcelo is a more dangerous attacking weapon than Kolarov -- not just a mere crosser and shooter but a genuine playmaker in his own right.
It is likely that Marcelo will need help from Sergio Ramos, Real's left-sided centre-back. He has a habit of providing crucial moments in big games in the opposition penalty area but is also excellent in terms of doubling up against a wide player, relying on his experience as a former full-back. If Madrid are to stop Salah, it might be about Ramos' display as much as that of Marcelo.
3. Will Liverpool score early?
A fundamental part of Klopp's game plan is for his side to put the opposition under pressure in the early stages. Liverpool effectively won their quarterfinal against Manchester City with three goals in the first 31 minutes, but those early exertions can cost them later in big games: They let Roma back into their semifinal with two concessions in the last 10 minutes of the first leg and twice conceded late in the return game.
The 4-3 Premier League win against Manchester City in January was another telling example: Liverpool forced early pressure in both halves and scored in the ninth minute of the first period, then the 14th, 16th and 23rd of the second. City, though, netted five minutes before half-time, then again in minutes 84 and 90. Liverpool's pressure dominated early, but City's possession took over by the end.
It's easy to imagine something similar happening vs. Madrid, and it's worth remembering that Klopp's previous Champions League final appearance, in 2013, also fits the pattern. His Dortmund side took early control against Bayern Munich -- the scoring sequence doesn't quite tell the story of the game -- but faded badly late and lost to a last-gasp Arjen Robben winner.
An early goal for Liverpool would compel Real to push forward and leave Liverpool space -- Klopp's side are the best counterattackers in Europe -- into which they can break. But if the English side fail to score in their expected period of early dominance and end up chasing the game, it will be extremely difficult in a physical sense to press aggressively later on.
4. What role do substitutes have to play?
Arguably the greatest contrast between these two sides is the resources available on the respective benches. This factor is another reason that Real are likely to dominate the latter stages, which means Liverpool must strike early.
Liverpool have suffered badly from injuries in recent months; Joel Matip, Alex Oxlade-Chamberlain and Joe Gomez are all out, while Nathaniel Clyne, Emre Can and Adam Lallana lack match sharpness after periods on the sideline, and James Milner is a slight doubt.
That means Klopp's replacements will be the aforementioned players who have struggled for game time recently or the likes of Danny Ings, Dominic Solanke and Alberto Moreno, none of whom will strike fear into Madrid.
Zidane, by contrast, has no absentees and no suspensions and therefore has options. With Casemiro, Kroos, Modric and Ronaldo four surefire starters in midfield and attack, it means only two of Bale, Isco, Benzema, Vazquez and Asensio will start. The other three will be in reserve, alongside the gifted Mateo Kovacic.
Real's substitutes have proven crucial in recent final victories: Marcelo, Isco and Alvaro Morata helped overload Atletico in 2014. Then Morata, Bale and Asensio put the result beyond doubt against Juventus last year.