Real Madrid's struggling defence will probably have to keep Bayern Munich's deadly striker Robert Lewandowski at bay in the Bernabeu to reach the Champions League semi-finals.
Real will be defending a 2-1 lead from the first leg of the quarter-final, which the Polish hitman missed with the shoulder injury that also kept him out of the German side's 0-0 draw at Bayer Leverkusen in the Bundesliga on Saturday.
However, Lewandowski trained on Sunday and is poised to return as Bayern look for goals on Tuesday against a Real side that have kept only one clean sheet in their last 12 games.
"I’m fine. I'm very pleased I was able to take part in training today. Everything's OK," said the Pole, who is Bayern’s top scorer with 38 goals in 40 games in all competitions.
Javi Martinez is banned after his first-leg red card, while Bayern may also be without the injured Mats Hummels and Jerome Boateng, who both missed the Leverkusen clash.
"Of the three (injured), Lewandowski has the better chance of being fit to play," said Bayern manager Carlo Ancelotti.
“It will be very difficult in Madrid but we still have confidence. We still have an opportunity and we'll do our best."
Lewandowski has seven Champions League goals, level with Borussia Dortmund forward Pierre-Emerick Aubameyang and only behind Barcelona's Lionel Messi (11) and Paris St Germain's Edinson Cavani (8).
He is also joint top of the Bundesliga scoring charts with Aubameyang on 26 goals this season.
Lewandowski joined Bayern from Dortmund in 2014, a few months after Real Madrid knocked the Bavarians out of the Champions League at the semi-final stage.
Bayern were thrashed 5-0 on aggregate three years ago but Madrid's defence is weaker now than it was then.
Pepe broke two ribs in this month's Madrid derby with Atletico and misses the Bayern game along with French centre-back Raphael Varane who still has a hamstring problem.
That leaves Sergio Ramos and Nacho Fernandez as the pairing at the heart of the defence for Real, who are also without forward Gareth Bale due to his calf injury.
Madrid last kept a clean sheet against minnows Alaves on April 2 and have not looked solid at the back all season.
They beat Sporting Gijon 3-2 on Saturday but conceded two sloppy goals, needing a 90th-minute winner from Isco to help them keep title rivals Barcelona at arm’s length.
"They had two chances and scored two goals," Real coach Zinedine Zidane said after the game. "(The players) all lost concentration, we weren't switched on for the free-kick (that led to Sporting’s second goal)."
The Madrid side could pay a high price for any similar slip-ups against Bayern, particularly with Lewandowski lurking.