Sneijder left the field on a stretcher after an hour following a heavy challenge by Arsenal midfielder Abou Diaby as the Primera Liga champions went down 1-0 - a result which handed the trophy to Hamburg, who beat Juventus 3-0 earlier in the day.

However, all that was overshadowed by Sneijder's injury.

"Undoubtedly he is not good," said Schuster. "We're all very worried about him.

"The truth is that this moment for him is very difficult. He is in a lot of pain.

"We still have to do more tests but it doesn't look good.

"I think it's better to wait and hear what the doctor has to say. That will be more complete, and clearer. But I can say that it is not good, he will be out for a while.

"It could be a cruciate ligament injury. We'll have to wait and see what the professionals say."

Sneijder is almost certain to miss the start of the new Spanish season.

"We're going to have to be without him for a bit," added Schuster.

"We now have go back home and recover our spirits from all this.

"But it is also something that happens in football. All great footballers have had these things and I'm sure he'll be back to normal soon."

While the two-day tournament is a friendly competition, the tackles which were flying in suggested the players were taking it as serious as any league match.

However, Schuster refused to attach any blame to Arsenal or Diaby.

"It's an English team and they play with a lot of intensity," he continued. "These things can happen. It's the way they play here and you have to accept that.

"The Emirates Cup is a tournament with very prestigious teams and they all want to give a good display and win.

"For that reason we had to be careful not to take risks and that's why the (Spain) internationals didn't play. It's a pity because it's a great tournament."

Sneijder's compatriot Arjen Robben also expressed his sympathy for his Madrid and Holland team-mate.

"We have to wait and see what's wrong," he said. "It looks very bad, very disappointing.

"He's a great player and a great person. We have to wait and see. Tomorrow he'll have a scan and we'll have to hope for the best."

Madrid have long been linked with Hamburg star Rafael van der Vaart and could increase their efforts to sign the midfielder in the wake of Sneijder's injury.

However, Robben refused to comment on whether he would be a fitting substitute.

"I don't want to speak about this," he said. "We only have to speak about Wesley.

"It's very disappointing for him, very sad. It's very sad news and we cannot speak about other players now."