The Manchester United and Argentina centre-back has aggravated a metatarsal problem, after needing surgery on the bone in April.
The club said he played with the injury in the defeats against Brighton and Bayern Munich after the setback occurred in the loss at Arsenal on September 3.
United medical staff are still assessing how best for him to recover and discussing whether a second operation might be the best course of action.
It means Martinez could be out until December, in the latest injury setback for the club.
Martinez’s injury means Harry Maguire, Victor Lindelof, or Jonny Evans will fill in against Crystal Palace on Saturday and for the foreseeable future.
Manager Erik Ten Hag is already without an out-and-out left-back after Sergio Reguilon was added to the treatment room this week.
