Ole Gunnar Solskjaer claims Manchester United will need up to five games to reach peak condition after such a short pre-season.
United looked well off the pace when losing their opening game of the campaign to Crystal Palace on Saturday.
They face Luton Town tonight in the Carabao Cup and Brighton at the weekend, with Solskjaer planning to ring the changes.
And he says it will be some time yet before his side reach the required levels.
“We need four or five games to get up to the standard we know we’re capable of,” he said. “We haven’t had an opportunity to get those games in and we have to make sure, in these games, we get the minutes and make the players ready to start competing in the league again.
“Brighton away is going to be a very tough one so we’ll use this one, we want to get through, but it’s also minutes for a few.
“We’ll make some changes, of course we will. For some, it’s the pre-season and, for some, they’ve only been here for a week now, for different reasons.
“Some of them need game-time, they do and we can see we’re lacking in sharpness. We just need to make the most of the training sessions and games we have.”
In Pictures | Manchester United vs Crystal Palace | 19/09/20
Dean Henderson starts in goal as one of 10 changes from the side beaten by Palace, with Jesse Lingard and Odion Ighalo in attack.
Solskjaer added: “No injuries, no fresh injuries after that game (against Palace), but, as I said, we’ll rotate and give some minutes.
“Some, after the game, will do some harder training this week to get ready for Brighton. Some will join the squad and go down there.”
Luton XI: Shea, Tunnicliffe, Bradley, Hylton, Shinnie, Moncur, Lockyer, Clark, Kioso, Norrington-Davies, LuaLua
Subs: Sluga, Cranie, Pearson, Cornick, Lee, Mpanzu, Collins
Man Utd XI: Henderson, Wan-Bissaka, Bailly, Maguire, Williams, Fred, Matic, Mata, Van de Beek, Lingard, Ighalo
Subs: Grant, Dalot, Mengi, Fernandes, James, Greenwood, Rashford
