The path to the Champions League final has been set. The draw in Nyon has thrown up the mouthwatering prospect of a Barcelona-Real Madrid final in Munich on May 19.
Before that, however, the two great Spanish rivals have to negotiate two other ties. Barca continue their defence against AC Milan, whom they faced in the group stage, while Real have the far more appealing task of playing APOEL Nicosia.
Assuming they both go through, Barca will play the winner of the quarterfinal between Benfica and Chelsea, while Real will play either Marseille or Bayern Munich in the last four.
Here are eight key battles—two for each tie—that will decide which four teams make it to the semifinals.
Anyone who has played certain editions of Football Manager will have taken great pleasure in seeing Dionisis Chiotis's heroic exploits for APOEL Nicosia this season.
The veteran Greek goalkeeper was a consistent bargain find in the PC game, and now the Cypriot minnows have borne that out in reality. The 34-year-old saved two penalties in the shootout victory against Lyon, which secured an unlikely place in the last eight.
All Chiotis has to do to see his team into the next round is stop Cristiano Ronaldo. Or, for the purposes of this slideshow, Cristiano "38 goals this season, second best player in the world" Ronaldo.
At the end of the knockout stage, the top scorer of this season's Champions League was not Lionel Messi, Mario Gomez or Cristiano Ronaldo, but APOEL striker Ailton.
True, the Brazilian had scored four of his seven goals in the qualifying rounds, but the fact remains. He has only scored twice in the Cypriot league this season, but if APOEL are to have any hope of beating Real, then they need all of their players firing on all cylinders.
Standing in his way will be Pepe, a fellow Brazilian by birth but now a Portugal international. The defender is notorious for his short temper and random bouts of violence. Such a mental short circuit, leading to a red card, could just be the catalyst for making one of the most incredible results in Champions League history possible.
This is more like it: a proper European Cup knockout tie. These two clubs have claimed the trophy 11 times between them, including five of the last nine seasons.
Lionel Messi's record haul of five goals in one match against Bayer Leverkusen has taken his European tally for the season up to 12. One of that dozen came against Milan in the group stage, in the 3-2 win at the San Siro.
Thiago Silva himself scored in the 2-2 draw at the Camp Nou that opened Group H, but Rossoneri will be relying on Silva's defensive excellence against the three-time World Player of the Year.
Zlatan Ibrahimovic only spent a year at Barcelona, but what an eventful one it was. He scored 14 goals in 29 league appearances as Barca won La Liga, but the big striker was unable to provide the"'Plan B," which he was bought at such great expense to do.
In addition, he fell out spectacularly with manager Pep Guardiola, famously telling him: "You bought a Ferrari but drive it like a Fiat."
Ibrahimovic was injured when Milan travelled to his former club for that group-stage opener. He's had 24 goals in Serie A and Europe this season, and Barca may be hoping he misses another return in the knockout phase.
Essien missed the first half of the season through injury, and upon his return, he found it difficult to win over Andre Villas-Boas.
Since the Portuguese manager was sacked, however, his fortunes appear to have changed. Interim boss Roberto Di Matteo was confident in the Ghanaian midfielder's abilities to start him in the crucial clash with Napoli, and the Blues duly won by the three-goal margin needed to progress.
Essien's next task in Europe will be to shackle Pablo Aimar, the experienced Argentinian playmaker who helped orchestrate the two draws with Manchester United that ultimately contributed to last season's finalists exiting at the group stage.
Another Benfica player who led to United's downfall was Oscar Cardozo. The Peruvian striker's goal just 24 minutes into their opening Group C fixture set the tone for the Red Devils' torrid form on the continent this season.
Cardozo has scored four goals in this season's competition to go with the 15 he has netted in the Portuguese league. Far worse strikers have given Chelsea's defence a hard time this season.
Terry, back after six weeks out with an injury in time to face Napoli in that crunch clash, will have his hands full when the Blues face the two-time European Champions in the quarterfinals.
Marseille managed to scrape their way through to the quarterfinals by beating Inter Milan on away goals, but they did so at a price. Goalkeeper Steve Mandanda was sent off after conceding a stoppage-time penalty and will now miss the first leg against 2010 finalists Bayern Munich.
In his place will most likely come Gennaro Bracigliano, OM's reserve keeper. His only appearance this season came off the bench after Mandanda's red card, with just enough time to concede Giampaolo Pazzini's penalty before the final whistle blew.
The 32-year-old will get a full 90 minutes here and must attempt to thwart Bayern's rampant attack, chief among them striker Mario Gomez. Gomez scored four goals in his last European game to take his total to 10 for the competition this season.
Bayern were given a welcome boost recently with the return of key midfielder Bastian Schweinsteiger, who has missed a good deal of the season with a ligament injury.
By the time the tie with Marseille kicks off on March 28, Schweinsteiger should be fully fit and restored to the side.
As such, the Germany international is set for a ding-dong with Alou Diarra, Marseille's midfield general and a crucial factor in the French side's hopes of scoring a significant upset.