After being held at the Nou Camp by Benfica, Barcelona’s chances of reaching the Champions League knockout stage are in jeopardy.
Yusuf Demir, on loan from Rapid Vienna, struck the crossbar on a dismal night for Xavi’s side.
Second-placed Barcelona had a goal disallowed, but they are still two points ahead of third-placed Benfica.
Barcelona will play Bayern Munich away in their last group game, while Benfica will host Dynamo Kyiv.
Both matches are scheduled for December 8, and it is expected to be a tough finish for the five-time European champions.
Barca have scored just two goals in five Champions League matches this season, despite being undefeated in their last three group games.
If Benfica win their final match and Barca lose in Germany, they will be relegated to the Europa League.