The Premier League side forked out a mammoth £40m to sign the Netherlands international from Ajax this summer but he is yet to start a Premier League game.
The 23-year-old has made only two starts since his move; in the Carabao Cup against Luton Town and Brighton, and has played only 61 minutes in total from the bench.
Van de Beek was an unused substitute in Manchester United’s stalemate against Chelsea over the weekend.
Questions have been raised as to why Solskjaer does not often play the Dutchman and the Norwegian coach has hit out at his critics.
‘Donny is going to play a big, big part this year,' said the former Cardiff City boss. 'At the moment, I realise the topic is Donny van de Beek and it's nice for some players or commentators to have a little go.
'I know you're short for time when you're on telly and you have to put your points across very quickly, but you have to know that you don't have to start the first three games to be a very important player in the squad.
'I'd be disappointed if some of my team-mates said I wasn't important at Man United, but I didn't start many games. So Donny's going to be very important for us, don't worry about that.
'When Donny has played, he's played really well. I think it says a lot about our depth of quality in the squad that we don't have to use him every single game because we have other players as well.
'I also think it says everything about our ambitions. We want to push on, we want to challenge for trophies this season.'
