Barcelona's Dutch winger Ibrahim Afellay will need surgery after tearing a ligament in his left knee during training, the club has announced.
"Bad news for Josep Guardiola and FC Barcelona," the club said on Thursday in a statement on its website.
"Ibrahim Afellay has torn a cruciate ligament in his left knee while training this evening. He will require surgery and further details will be revealed tomorrow (Friday) regarding how and when."
It is another injury blow for the Dutchman who had recently returned to fitness after picking up a hamstring injury in the preseason. The 25-year-old has played just a substitute's role this season, appearing in games against AC Milan and Osasuna.
Afellay was signed from PSV Eindhoven in December.
Guardiola's squad have already been hit by injuries to Andres Iniesta and Alexis Sanchez as the club lie in fourth place behind Seville's Betis, Valencia and Malaga.