Manchester United manager David Moyes has admitted his frustration at not being able to play Juan Mata in their Champions League campaign.

The Spain international midfielder, who joined the Red Devils from Chelsea for £37.1m in January, will be unable to feature in the knockout rounds of the competition this season as he is cup-tied, having already played in the group stage for the Blues.

"We wanted to get Mata when we could and that was the January transfer window," the Daily Star quotes Moyes as saying.

"Yes, it's a frustration we can't use him in the Champions League and that's why you hear people saying January isn't a great time to buy. Most of the clubs are trying to buy players who aren't Champions League cup-tied.

"But the better ones tend to be – like Juan. We are trying to buy that type of talent, so as I say, we wanted to get him early when we could."

United will travel to Athens this week for the first leg of their last-16 tie against Olympiakos on Tuesday.