The Portuguese bek was injured during the Confederations Cup match with Russia, which was the last for him at this tournament.
It was expected that the football player received a bruise and survived the relapse of the old injury, but a detailed examination showed that Guerreiro fractured ankle.
"Rafael Guerreiro suffered a surgical intervention. The 23-year-old will play outside the game for three to four months, "- said the official Twitter of Borussia.
In the season that ended, Guerreiro spent 35 matches for Borussia in all tournaments, scoring 9 goals and giving 9 assists.