Barcelona have confirmed that Andreas Christensen picked up an ankle ligament injury during Tuesday's Champions League contest with Inter Milan.
The Denmark international was substituted just before the hour at San Siro, with Gerard Pique entering the field as his replacement.
On Tuesday evening, the Catalan outfit said that the 26-year-old had picked up "a ligament strain", with further tests set to take place on Wednesday to determine the extent of the damage.
"Andreas Christensen has a ligament sprain in his left ankle. Further tests will be carried out tomorrow to find out the exact extent of the injury," read a statement from Xavi's side.
Barcelona have not put a timeframe on his potential absence, but according to AS, the Dane is facing three weeks on the sidelines.
As a result, he could be absent for the team's next five matches against Celta Vigo, Inter Milan, Real Madrid, Villarreal and Athletic Bilbao.
Barcelona already have issues when it comes to the middle of their defence, with Ronald Araujo out until at least November following thigh surgery, while Jules Kounde is missing due to a hamstring issue.
Xavi's side currently only have two first-team centre-backs fit and available - Pique and Eric Garcia - while the team's options at right-back are also limited due to Hector Bellerin's injury.
The one-goal defeat at San Siro has left Barcelona in third spot in Group C, three points behind second-placed Inter and six from leaders Bayern Munich.
Hakan Calhanoglu scored the only goal of the match in the European affair, but it was a controversial win for the home side, as Barcelona had a Pedri effort chalked off for an Ansu Fati handball, while the visitors had a big penalty shout when Denzel Dumfries handled inside the box.
After the match, Xavi said that he was "angry" with the decisions that had been made in Italy.
"I'm angry. The referees should come out and explain their decisions because we don't understand anything. I asked the referee to explain his decisions after the match and he refused. What we lived today is injustice," he told reporters.
"They told me that Pedri's goal should have counted. It is a legal goal. In Pedri's goal, after Ansu accidentally touches it, the rule says that a new play starts from that moment. So it should be considered a legal goal.
"The referee left and said nothing. I'm outraged. We don't understand. That is the word, outraged."
Barcelona will be bidding to bounce back from the defeat when they welcome Celta Vigo in the league this weekend before hosting Inter in the Champions League next week.
