Barcelona defenders Gerard Pique and Sergi Roberto face long sidelines after tests confirmed they had knee and hamstring injuries respectively.
Both were injured in the 1-0 league loss to Atletico Madrid on Saturday.
Examinations on Sunday revealed Pique had a grade 3 sprain to the medial lateral ligament and a partial injury to the anterior cruciate ligament in his right knee. Right-back Sergi Roberto has a hamstring fracture in his right leg.
Barca have not revealed how long Pique will be out of action, although there is speculation that the 33-year-old center-back could be sidelined for at least eight weeks. They have confirmed that Sergi Roberto will need around two months to recover.
Pique and Sergi Roberto have each made 10 appearances for Barca this season.
Clement Lenglet is the only center-back in form for Tuesday's game at Dynamo Kiev in the Champions League. Samuel Umtiti and Ronald Araujo are unavailable due to other fitness issues.
“I'm worried like any coach,” Barca boss Ronald Koeman said after Saturday's game when asked about the latest injuries. “There are a lot of injuries because of the schedule we have.
“We have to wait and see how long they'll be out, but I'm clearly worried.”
Barca are also without Sergio Busquets, who injured his knee while on international duty with Spain, and Ansu Fati, who recently had knee surgery.