Little over a month after producing the greatest comeback in Champions League history, Barcelona need another special turnaround as they face Juventus in the second leg of their quarter-final on Wednesday.
Luis Enrique's side were taken apart in the first leg in Turin, losing 3-0 to a Juve team inspired by Paulo Dybala, who scored twice.
In the last 16 they became the first team ever to overturn a 4-0 deficit when they beat Paris Saint-Germain 6-1 in the return at the Camp Nou, so fans are hoping for a similar "remuntada" this time.
"We are going to take as many risks as we need to the point that we could go out with eight strikers, as we have nothing to lose," said Luis Enrique after Saturday's 3-2 defeat of Real Sociedad.
The Barcelona coach also called for supporters "to have faith in these players who have won everything. This is a squad of champions."
But he added: "The thing is that we are used to always eating beluga caviar. That can't go on forever."
Barca welcome back midfielder Sergio Busquets from suspension, while Juve are hopeful Dybala will be ready after he came off in the 2-0 weekend win at Pescara with a sprained ankle.
"We have four days and we need to be optimistic," declared coach Massimiliano Allegri.
In contrast to their fierce rivals, Real Madrid are very much on course for a semi-final berth after their 2-1 win away to Bayern Munich last week.
The sides clash at the Santiago Bernabeu in Tuesday's second leg with the Germans looking to become just the third side to overturn a first-leg home defeat to win a Champions League tie.
Bayern coach Carlo Ancelotti has fitness concerns with leading scorer Robert Lewandowski hopeful of returning from a shoulder injury.
Defenders Mats Hummels and Jerome Boateng are also fighting to be fit, while Javi Martinez is suspended.
"We go to Madrid well aware of the fact that nothing is impossible," Thomas Mueller told Bundesliga.com.
"We're annoyed any time we don't win, but we have our own way of playing. No matter what problems or injuries we have to deal with, we're always able to put a strong team out there on the pitch."
Gareth Bale is struggling to shake off a calf problem for Real, who have lost just twice in 12 past home meetings with Bayern.
- Dortmund test of character -
Borussia Dortmund go to Monaco still shaken by the events of last week, when the first leg between the clubs was postponed by 24 hours following the bomb attack on the German team's bus en route to the game.
Dortmund went on to lose 3-2 to the French league leaders but morale was lifted as they got back to winning ways in the Bundesliga at the weekend, beating Eintracht Frankfurt 3-1.
After that game, the Dortmund players paid tribute to defender Marc Bartra by holding his number five shirt aloft as they celebrated in front of their fans.
Spanish international Bartra had earlier been released from hospital after having surgery on a broken wrist suffered in the attack.
"This gesture shows how important the things off the field are to us at this moment, and that Marc gets better soon and that we are all still here," said Dortmund captain Marcel Schmelzer.
Monaco, looking to become the first French side in the Champions League semi-finals since Lyon seven years ago, are missing the banned Fabinho as well as Djibril Sidibe, who is recovering from appendicitis.
Leicester City have defensive concerns as they look to turn around a 1-0 deficit when they host last season's runners-up Atletico Madrid.
Robert Huth is suspended and the Foxes are hoping Wes Morgan can return from a back injury as the English champions look to extend their run in Europe. Atletico have French striker Kevin Gameiro back from a groin injury.