But the clueless Twitter trolls failed to take into account that £37m record signing was CUPTIED.
Rumours have emerged from New York today that Moyes could be about to leave United by mutual consent, although Starsport understands his position to be safe.
Mata was in the Chelsea squad for their Champions League campaign so cannot turn out for his new club.
It didn’t stop Moyes for being hammered for not playing him, though.
Disgusted tweeters couldn’t believe Mata wasn’t playing and called for Moyes to be sacked.
United were well off the pace against Olympiakos and fell to a shocking 2-0 defeat.
Moyes had defended his decision to sign Mata despite knowing he would be ineligible for the Champions League.
“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.”
– Daily Star