PSG take on the European champions at Parc des Princes on Tuesday and are without the services of their world-record signing Neymar for the crucial fixture.
And now, after beating Marseille 3-0 on Wednesday to reach the Coupe de France semi-finals, Kylian Mbappe, another key member of their attack is said to be a doubt for the Los Blancos fixture after being substituted for midfielder Javier Pastore due to a foot injury.
The France international has enjoyed an incredible debut season with the Ligue 1 leaders, with 16 goals and 14 assists to his name in 33 appearances across all competitions - and will be a huge blow for manager Unai Emery, who will now rely on top-scorer Edison Cavani against the LaLiga giants.
Mbappe, 19, joined the club on a season-long loan from domestic rivals AS Monaco in the off-season and will become the second most expensive transfer in football history in the summer when PSG activate the £165.7m (R2.7b) clause to make the deal permanent.