Rafael da Silva may be out for five weeks due to the hamstring injury he suffered during Manchester United's victory over Wigan Athletic.

But Wilfried Zaha could still be available for England's friendly with Scotland at Wembley on Wednesday, despite the leg problem that caused him to be substituted in the Community Shield game.

The news regarding Da Silva is a blow to David Moyes, who is now likely to be without his first-choice right-back for the difficult start to United's championship defence that features Swansea City, Chelsea, Liverpool, Crystal Palace and Manchester City in the opening five games.

Asked what the problem was, Da Silva said: "A hamstring, I could be out four, five weeks." Moyes confirmed that the Brazilian could be out for a lengthy period. "Rafael has a bit of a hamstring injury," he said.

Of Zaha, who has featured in all of United's pre-season games as he settles in at the club after his £15m move from Palace, Moyes said: "He got an injury just at the [second] goal. I think this is what's going to happen. This is a boy that's come right out of the Championship, he's done well in the pre-season games and we felt it was right that he got an opportunity today. He's going to develop but he'll be a bit up and down, but it was a great opportunity for him to get on the pitch for Manchester United. I'm really looking forward to working with him and improving him and I'm sure we'll use him as the season goes on. He's a young boy. I think he'll be all right for England. I really don't know what the injury was that he came off with."

With the unsettled Rooney recovering from a shoulder problem – though he will feature for England – and Nani, Ashley Young and Javier Hernández also nursing injuries, Moyes is conscious of the need to rotate his squad wisely. The manager is particularly cautious regarding Robin van Persie, last season's top-scorer.

"We have to be aware of how often we can use him. We'll try to use him to the best of our ability. We've got other centre-forwards. As you know, Wayne wasn't fit and Chicharito [Hernández] had an injury. We're just a little bit short at the moment."