Samuel Umtiti will undergo an operation after breaking his foot in training on Monday, Barcelona said.
Umtiti's latest injury reduces the chances of him leaving in the January transfer window, with Barca looking to ease the club's enormous debts by moving players on this month.
The France defender has been on the fringes of Barcelona's first team for a while.
His form has been affected by a string of knee injuries and the 28-year-old has made only one start in La Liga this season.
Barca announced earlier this month that Umtiti had signed a new four-year contract.
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The deal was aimed at spreading his wages over a longer period, which enabled the club to register new signing Ferran Torres within this season's spending limit.
The length of Umtiti's absence will be more accurately gauged after his surgery on Tuesday, Barcelona said.
"Samuel Umtiti suffered a trauma during today's training session on his right foot which caused a fracture in the fifth metatarsal," read a club statement.
"The player will undergo surgery on Tuesday."