The Bulgarian international suffered the setback against Atlante in the Peace Cup on Wednesday and underwent a scan after flying back home.

Now it is touch and go whether he will be fit for the Barclays Premier League opener against Wigan on August 15.

Petrov said: "I've landed awkwardly on my shoulder and it's just come out.

"It's especially frustrating as it's pre-season but that's the way it goes.

"I just have to accept it. It's part of the game. We're hoping that it will only be a few weeks before I can start training again."

"There's no swelling there. It's just come out and popped in.

"You know with shoulders sometimes a lot of players can pop them and be in a lot of pain and then a few weeks later it's fine and you can play again."

Petrov added: "I've never done it before. With me it's one of those ones where we have to wait and see.

"Everybody's frustrated when they're injured but that's part of the game and I'll accept these things. I'll be working hard, I'll be fit again and I'll be back."

Petrov is a prime candidate to be Villa's new captain in succession to Gareth Barry and he led the team in the Peace Cup before his shoulder blow.