United were well short of fitness and quality as they lost their opening Premier League game of the season 3-1 at home to Crystal Palace last weekend.
Solskjaer's rotated team recovered somewhat with a 3-0 Carabao Cup victory at Luton Town, but that performance was still a long way off where United need to be at this point.
Brighton are up next for United, and the Seagulls are one a three-game winning streak - including two Carabao Cup ties - after losing their opening game at home to Chelsea.
Summer signing Donny van de Beek played the majority of the Carabao win in Luton and was back in training with the likes of Paul Pogba on Thursday, though the Dutch international could be on the bench at Brighton.
Scroll through the gallery above for the latest pictures from Carrington...