"Starting would be too much, I think, at this point, [for Mason]," Carrick revealed at a press conference to preview Friday night's Premier League clash at Bournemouth.
"Just for the training time and the exposure he's had, really. But it's brilliant to have him back. He's a fantastic player, Mason, and great to have around the group again.
"So [I'm] delighted to have him back and, obviously, the break coming up now gives him a chance to get even more up to speed.
"So, in some ways, that's come at a good time for him."