Before the first leg of this tie, Jose Mourinho's ability to learn from previous matches was widely touted -- the expectation being that his Real Madrid side could reverse the results from the last time they played Borussia Dortmund in the Group of Death. But what he did at Inter, conquering Barcelona in the semi-finals having tasted defeat in the group, was not replicated. Instead, Madrid were on the receiving end of Robert Lewandowski's stunning four goal haul, which set the tone for one of the most one-sided Champions League semi-finals of all time. Now Mourinho's ability to learn from past mistakes will face its greatest test.
"I named my team before the first leg because it was obvious. This time we might try different players and a different system so I won't say." This is Mourinho being typically cryptic and while one can't rule out a surprise selection, the expectation is for all his words that he will select the 'usual' Madrid team. That would see Cristiano Ronaldo, Mesut Özil and Angel Di Maria starting behind Gonzalo Higuain - Real Madrid's strongest team on paper, and the attack most capable of scoring goals.
That is precisely what Madrid need to do in this tie. Neither of last week's semi-finals were the stereotypically cagey European clash that had become customary on the continent. Instead, Madrid need to reverse a three goal deficit, only heartened by the fact Ronaldo's tap-in late in the first half counts as a vital away goal. But that advantage will be wiped away if Dortmund score in the Bernabeu.
As ever in football, balance will be key. Mourinho can't instruct his players to go flying forward in attack, knowing that Dortmund are devastating on the counter-attack. The problem is, the two major problems that cost them last week are intrinsically linked to their need of attack.
First of all was the problem of Ilkay Gundogan, who, as one of the two midfielders in Dortmund's double pivot, linked the midfield to the attack with clever, positive passes. His influence over the contest was surprising, given Mourinho had switched to 4-3-3 with Luka Modric sitting in front of Xabi Alonso and Sami Khedira. The Croatian's regista style means he operates in deeper zones than Madrid's regular no.10, Ozil, so they should have been better equipped to deal with Gundogan's excellent distribution - but instead, the Dortmund midfielder enjoyed great time on the ball, and set the tempo excellently.
Although Ozil is not ideal for tracking Gundogan, he must start in a central position, for the sake of fluidity in attack. The German's greatest attribute is his intelligence - he's always searching for space, drifting deep to drag away midfielders, drifting wide to open up room for Di Maria and Ronaldo. Ozil playing wide on the right in the first leg inhibited the freedom of Ronaldo, to drift inside, and perhaps even more crucially, Ozil was never able to receive the ball in threatening positions, given that his movement inside was very obvious, and tracked easily by Sven Bender.
The second issue for Madrid is the isolation of the full-backs. Mario Gotze's lateral movement into wide positions - the role that Ozil normally plays - exaggerated Dortmund's dominance in those areas, with Marco Reus and Jakub Blaszczykowski thriving on the support. With Gotze helping to overload Fabio Coentrao and Sergio Ramos, the two Dortmund wingers were free to drive directly on goal.
Madrid's problem was twofold. Firstly, the wingers stayed high up the pitch and offered little protection - his is not a problem in the league but has been a significant issue for Mourinho in Europe, where the opposition is naturally more skilled.
Secondly, the Madrid double pivot had enormous trouble keeping tabs on Gotze, who was, by the nature of the formation battle, the designated player in their zone. But by constantly drifting wide to the spaces on either side of the midfielders, there was confusion about who was responsible for marking him.
The natural response would be to instruct the wingers to play a little deeper, and help form two solid banks of four. The irony is that in any other scenario this might have been a possibility. Instead, Mourinho must encourage his side to attack, even if that means the wingers stay high up, and Gundogan is left unmarked - the two issues that have led directly to this scenario.