Eden Hazard missed Real Madrid's narrow win over Getafe on Thursday and will also sit out the game away at Athletic Bilbao on Sunday.
Zinedine Zidane says he's been suffering as a result of a blow he received in last weekend's 1-0 win over Espanyol in Barcelona.
"Eden's having a tough time and we don't want to risk anything, and he's the first [to agree]," Zidane said in a press conference on Saturday.
"Hopefully it's a small thing and we can see him again before the end of the league [season]. He's missed training for three or four days and I hope he'll get over it quickly.
"It's the day to day, we don't know anything more than it's a strong blow. There are those who know, the doctors and the physicists... there are very competent people.
"It was a knock against Espanyol and hopefully it's a matter of days."
Hazard's first season at Madrid has been blighted by injuries. He has missed a large chunk of the campaign since his 100 million euro move from Chelsea last summer.