Junior Firpo will not be fit to play Inter on Wednesday, a match for which Jordi Alba is already sidelined.
Barcelona are facing a full-back crisis ahead of their Champions League clash with Inter after Junior Firpo was ruled out with a hamstring injury.
The 23-year-old had tests after feeling discomfort during training on Tuesday, which have confirmed he has muscle damage.
First-choice left-back Jordi Alba (hamstring) was already unavailable due to injury, as was Samuel Umtiti (foot), another possible option on the left of Ernesto Valverde's defence.
With Junior out, it means Barca will likely have to field either Nelson Semedo or Sergi Roberto at left-back, with Clement Lenglet and Gerard Pique expected to start at centre-back.
Valverde could also bring in 20-year-old right-back Moussa Wague, who has twice been on the bench for Barca in LaLiga this season, or central defender Jean-Clair Todibo as makeshift options on the left.
Barca, Inter, Borussia Dortmund and Slavia Prague all have one point after the first round of matches in Group F.
The Catalans have lost only one of their past nine matches against Inter, who have been beaten in five of their last six visits to Camp Nou.