Pirates reliever Kyle Crick suffered a season-ending finger injury in an altercation with closer Felipe Vazquez, the team announced on Tuesday.
According to the release, the incident happened in the Pirates clubhouse prior to Monday's game against the Giants.
Crick underwent surgery to repair his tendon in his right index finger as a result of the fight.
"The behavior exhibited by these two players last night is unacceptable, inconsistent with the standards expected of a Major League player and will not be tolerated by the organization," general manager Neal Huntington said in the statement.
The Pirates said both players have been fined for an undisclosed amount. Crick was suspended earlier this season for his role in the benches-clearing brawl against the Reds in Cincinnati.
Crick is expected to return in time for spring training.