Real Madrid right-back Dani Carvajal is facing a month of the sidelines after the club confirmed the Spain international sustained a hamstring injury.
Carvajal suffered the muscular problem in training this week and did not feature in the 2-1 defeat to Celta Vigo in Wednesday's Copa del Rey quarterfinal first leg.
A Real Madrid statement read: "Following the tests carried out today on Dani Carvajal at the Sanitas La Moraleja University Hospital, he has been diagnosed with a grade 2 injury to his right biceps femoris."
AS reported that Carvajal will be out of action for three or four weeks, but Real have not confirmed the length of his absence.
The 25-year-old, who has started in 23 games for Los Blancos in all competitions this season, is set to miss his team's next four La Liga games and the Copa quarterfinal return leg at Celta on Jan. 25.
Real Madrid coach Zinedine Zidane will be hoping to recover Carvajal in time for Real's Champions League round of 16 first leg against Napoli on Feb. 15.
Meanwhile, goalkeeper Kiko Casilla is confident Real can get back on track following successive defeats.
Los Blancos endured their first defeat in nine months at the weekend when they lost 2-1 to Sevilla, a setback that brought an end to a 40-game unbeaten streak, before Wednesday's loss to Celta, their first home reversal since Feb. 27, 2016.
"Just one week ago we were considered fantastic when we drew at Sevilla in the Copa, but now we are the worst in the world," Casilla told Marca. "We were not the best then and we are not the worst now.
"We have lost two games and we haven't had a good week. The important thing is that we are Real Madrid and we cannot allow this to bring us down. We are very united and a strong group. I'm certain we will bounce back immediately."
Real fans expected a lot more from Cristiano Ronaldo, who was given a rare start in the Copa against Celta.
The four-time Ballon d'Or winner lacked precision and had just two shots on target that did not trouble Celta goalkeeper Sergio Alvarez.
Real fans interviewed by AS after the game expressed their overall discontent with the team and with Ronaldo and the majority agreed that the Portugal captain "disappeared in the game, looked lost and out of form" and should not have played.
Two supporters suggested that if a €100 million offer were to arrive from China for Ronaldo that Real should sell him in reference to recent reports that the 31-year-old forward had received a mega offer from an undisclosed team from the Chinese Super League.
Another supporter agreed and said that Real "have relaxed too much" and that the club should sell him and bring new players and suggested Bayern Munich striker Robert Lewandowski.
Real are one point clear of Sevilla at the top of La Liga and have a game in hand. They are at home to Malaga on Saturday.