The England midfielder sustained the injury during training earlier this week and will sit out a string of games as new manager Louis van Gaal starts his reign at Old Trafford.
The Dutchman revealed the news during his first press conference, admitting the loss of one of United's long-serving players was an early 'blow' to his preparations.
“Michael was injured the day before and that's a blow for me because he's experienced,” he said. “It's very important we have experienced players.”
Carrick will be absent as United’s squad depart on Friday for their tour of the United States, where they will take part in games against LA Galaxy, AS Roma, Inter Milan and Real Madrid.
@chrissb7, alongside who? Kagawa isn't a replacement for Carrick, he's not even a central midfield player in that sense. Unless LvG pulls something out of the bag it will be one from Fletcher, Cleverley or Fellaini to line up alongside Herrera. Blimey, remember the days when Nicky Butt was looked upon as the poor relation of the United midfield? He'd walk into the team now.- Mike_Christie