The Japan international was substituted during the Champions League win at Old Trafford after sustaining the knee problem.
“It’s a knee injury similar to the one Ashley Young had but not as bad,” said United boss Sir Alex Ferguson ahead of United’s trip to Chelsea on Sunday.
“I think playing on with the injury did not help the situation for him, even though he did well to play on with it. It’s disappointing for him.”
Ferguson also confirmed that Chris Smalling is back in training and that Phil Jones is nearing a return.
“Smalling is back training on the football side of things,” added the United boss. “Phil Jones will hopefully start full training a week on Monday so things are getting better on that front.
“Certainly getting Smalling back is a big bonus for us. Other than that, everyone else is available for Sunday’s game.”
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