The 'ace' in question is City's French midfielder Antoine Sibierski who is available on a free transfer.
Stuff you might need to know:
He's 32
He scored two goals for Citeh last season.
Apparently, he's dead skillfull and can catch the ball on his neck and everything!
Moyes is a 'big admirer' of him.
Expect him to jib Wigan off in the next few days.