Ole Gunnar Solskjaer plans to rotate his squad for Saturday's FA Cup tie against Wolves with the League Cup semi-final against Manchester City coming up on Tuesday.
The clash at Molineux will be United's fourth game in nine days in all competitions and with injury and illness affecting the squad, and the first leg of the semi-final against City coming up at Old Trafford on Tuesday, Solskjaer said he will be looking to rotate his team for Saturday evening's game.
"Yeah, you have to (rotate). That's the only logical and sensible solution because players, you've got to respect what they're doing - physically and mentally - what they're doing," he told MUTV. "Running round, it's high intensity. Football's changed so much since I played. There will be some changes. It has to be.
"You see Brucey (Steve Bruce) for example, he got four hamstring injuries in one game, you see Harry Kane got his hamstring, so we need to look after the players."
And Solskjaer could be forced into more rotation than he was planning with a number of players set to miss the third round tie.
Paul Pogba and Scott McTominay are out while defenders Eric Bailly (knee), Timothy Fosu-Mensah (knee), Axel Tuanzebe and Marcos Rojo are also unavailable.
Jesse Lingard and Anthony Martial are also doubts due to illness. Both arrived at the training ground on Friday but left 15 minutes later as both are unwell. United are believed to be keen for players who are unwell not to be on site before games.