The United boss recently bemoaned his side's busy schedule, but former club captain Roy Keane has lambasted Mourinho, and suggested that the former Chelsea boss could be overwhelmed by how big the Manchester club is.
"I've never heard so much rubbish in my life. Why do we have to listen to that garbage? It's just utter nonsense what he's talking about," the Irishman told ITV.
"He's manager of Manchester United, one of the biggest clubs on the planet, the squad he's got, the players, and he keeps moaning about fixtures and fatigue.
"We were just looking at some of the cup draws they've had. They've had an easy way in the cups, some good draws, a lot of home draws, and the guy is talking absolute nonsense.
"I've never heard so much rubbish in my life. Maybe the club is too big for him, he can't deal with all these demands at the match. What matches? Man United reserves could've won that game."