Barcelona defender Gerard Pique suffered a potentially serious knee injury in Saturday's LaLiga contest with Atletico Madrid.
Atletico forward Angel Correa awkwardly fell on top of Pique's lower leg after being tackled, causing to bend the wrong way at the knee.
Pique was left in visible pain and seemingly unable to walk unaided.
The centre-back hobbled off the pitch thanks to the assistance of medical staff, but the look of anguish across his face was mirrored by one of concern on coach Ronald Koeman.
Barca were 1-0 down at the time of his withdrawal.
In a show of support, Pique's former defensive partner for Barcelona and Spain, Carles Puyol, tweeted: "Forca @3gerardpique I hope it's nothing."