Atletico Madrid forward Adrian fractured a cheekbone in Wednesday's 3-1 Champions League victory at home to Zenit St Petersburg and will have surgery to repair the damage later on Thursday, the La Liga club said.
In the absence of the suspended Diego Costa, Adrian started the match at the Calderon in a two-pronged forward line with David Villa but had to come off 12 minutes from time after sustaining a blow to the face.
The 25-year-old would be operated on by facial surgeon Pedro Llopis at a clinic in Madrid on Thursday afternoon, Atletico said on their website (www.clubatleticomadrid.com). They did not provide an estimate as to how long he might be sidelined.
Coach Diego Simeone was delighted with Adrian's performance against the Russian side and the player was given a rousing ovation by the fans when he was replaced by Leo Baptistao.
"He is an extremely important player for us and his work was exactly what the team needed," Simeone told a news conference.
"He showed how to play a match with restricted space and use his speed in the best way," added the Argentine, a former Atletico midfielder who also captained his country.
"I am happy with his work, which we need, and he is a popular member of the group.
"Hopefully the support he is getting will generate the confidence you have to have to keep improving."
Adrian, who has made two appearances for the Spanish national team, is Simeone's third-choice forward and was reportedly considering quitting Atletico in the close season.
Atletico are the only team along with champions Barcelona to have won their opening four La Liga matches and play at Real Valladolid on Saturday (2000 GMT).