Bernal, 17, suffered an ACL setback before the international break.
The teen went under the knife on Monday as his club announced: "The player Marc Bernal has undergone a successful surgical procedure on the injury to the anterior cruciate ligament and lateral meniscus in his left knee carried out by Dr. Joan Carles Monllau under the supervision of the Club’s Medical Services at Barcelona Hospital.
"Recovery time is expected to be 12 months.
"The young midfielder started the game against Rayo Vallecano in week of La Liga and in added time at the end of the second half he was involved in a passage of play that led to him ending the game injured. In the following days a ruptured anterior cruciate ligament in his left knee and an associated injury to the lateral meniscus was diagnosed."