Bartra out of Barca's trip to Spartak Moscow
The 21-year-old youth academy graduate, who has been used as cover during the absences through injury of Carles Puyol and Gerard Pique, will be out for between 15 and 20 days, Barca said in a statement on their website.
Puyol and Pique played together in central defence for only the third time this season in Saturday's 3-1 La Liga win at home to Real Zaragoza.
Pique returned recently from a foot injury, while Puyol was back after 45 days out with a dislocated elbow.
Barca, seeking a third European crown in five years, top the group on nine points from four of six matches and will go through to the last 16 with a draw in Moscow.