The Spanish playmaker scored in the 4-1 rout of Girona in La Liga on Sunday but was later substituted after sustaining the injury.
“Tests conducted this Monday morning on Dani Olmo have revealed that the Barcelona forward has injured his right hamstring,” said Barcelona in a statement.
“He is expected to be unavailable for the next four to five weeks.”
Dani Olmo will miss Barcelona’s opening Champions League matches against Monaco and Young Boys, as well as several La Liga games and Nations League matches for Euro 2024 winners Spain against Denmark and Serbia in early October.
The 26-year-old could return for visit of Bayern Munich on October 23 and the Clasico clash at Real Madrid on October 27.
Dani Olmo has three goals in three matches for Barcelona since joining from RB Leipzig this summer.
