Real Madrid stars Gareth Bale and Luka Modric are both at risk of missing El Clasico after picking up injuries during Wales' 1-1 draw with Croatia on Sunday.
Bale was seen indicating he had hurt his left leg during the Euro 2020 qualifier, although he did manage to complete the full 90 minutes.
However, the same could not be said for Modric, who was forced off with a knee injury after a collision with Wales' Harry Wilson.
Wales boss Ryan Giggs confirmed after the game that Bale, who picked up a knee injury earlier in the international break, had been dealing with cramp during the game, but it was the winger's decision to carry on.
The belief is that Bale may be forced to miss Madrid's next La Liga game against Real Mallorca, but he could return in time to play a key role against Barca.
However, Modric's chances of featuring in the game appear to be slightly worse. A member of Croatia's medical team, Nikola Jerkan, did his best to play down the severity of Modric's injury, but the midfielder is set for further tests to try and discover the extent of the knock.
"According to the doctors, Modric has had a painful knock to the quads," Jerkan said. "It's logical that people are worried about the Clasico, but it doesn't seem very bad."
Modric himself played down the knock, telling Gol.hr: "I got a knee in the muscle. It's a little painful now, but I don't think it's anything serious. I feel better right now, but I believe it will be fine."
Madrid boss Zinedine Zidane will certainly be sweating over the fitness of Modric. Los Blancos have endured a real injury crisis since the start of the season, and they are yet to return to full strength.
Toni Kroos is currently sidelined, while James Rodríguez is also dealing with his own fitness issues, meaning Zidane may be forced to turn to Isco and Federico Valverde until Real are back at full strength.