Louis van Gaal
Van Gaal is facing a fitness crisis at United less than a month into his tenure.Getty Images/Clive Brunskill

Manchester United's new era under Louis van Gaal is threatening to be overshadowed by a fitness crisis with seven first-team players expected to miss the Premier League opener against Swansea City this weekend.

Jonny Evans, Luke Shaw and Antonio Valencia are the latest additions to an injury list which already includes Michael Carrick and Robin van Persie, while both Marouane Fellaini and Adnan Januzaj are short of match-fitness having each played just 14 minutes of football since the World Cup.

The significant losses leave a gaping hole in an already unbalanced and thread-bare United squad which Van Gaal has supplemented with just two signings in the summer transfer window, and the former Netherlands coach is concerned by the resources available to him.

"At this moment, we are fitter than our opponent," the 62 year old. "You could see that. But it was also the changes. Fellaini and Januzaj have only been with us training for one week. They can't play any more minutes than they did tonight.

"I had a lot of young players. They did reasonably well but they could do better, I believe. But it's a start. It's not easy to play at Old Trafford for the first time so I'm pleased we've won the game against a very good team. Of course, I think we have to make better choices with our passing - we didn't do that and that's a pity.

"We have a lot of injuries now. Don't forget, Jonny Evans was injured, Luke Shaw was injured, Antonio Valencia was injured. These are three defenders. We have to wait to see if they can play on Saturday. The main thing is that we have won, despite playing our worst game."

Carrick suffered ankle ligament damage in Van Gaal's first official week as United manager while Van Persie has been given a personal fitness programme to assist in his return from having played seven matches at the World Cup.

Both Fellaini and Januzaj were absent from United's pre-season American tour and featured for the first time this summer against Valencia, but neither are likely to be available having played for just a handful of minutes on Tuesday evening.