كتب : Ahmad Saied
Carrick left the pitch on crutches on Saturday after only 16 minutes in action during his side's 1-0 friendly victory over Ajax Amsterdam.
"It looks like he'll be out for a few weeks," United's official website quoted Sir Alex Ferguson as saying.
"There was immediate swelling and a lot of bleeding. It's the front ligament."
Carrick joined Old Trafford from Tottenham Hotspur for $35.2 million and Ferguson believes he can fill in the space left by former captain Roy Keane.
But he is now placed on the injury list that also includes Gary Neville, Nemanja Vidic and Gabriel Heinze, all out of the Premiership opener against Fulham on August 20th.
Ferguson said the injury left the English international disappointed but stressed the team can cover his absence.
"It is a real blow for the young lad. He wanted to do really well for us and this has knocked him back a bit," he said.
"But we have to handle it. Injuries are part of the game and we have plenty of good players in the squad who can take his place."