USA captain Landon Donovan is convinced Manchester United striker Wayne Rooney is burned out.

Rooney has been troubled by an ankle and groin injuries in recent weeks, the latter of which forced him off early in Manchester United's final Barclays Premier League encounter with Stoke last weekend.

That match was Rooney's 49th for club and country in a season when the 24-year-old has shouldered United's hopes like no other time during his Old Trafford career.

And Donovan, who will lead the United States against England in their World Cup opener in Rustenburg on June 12, believes Rooney is showing signs of being "worn out" after his heavy workload.

"Rooney is a top player. In my opinion, he is one of the best players in the world right now," LA Galaxy captain Donovan, who enjoyed a successful loan spell with Everton, told Yahoo! Sports.

"But the other part of it is that he has played a lot of games and he is tired. He is probably worn out.

"Injuries are a part of that. Things happen when players are tired. When they just keep adding games to the schedule, it makes it difficult.

"Any time you come into a World Cup, because of the timing of it, big players who play a lot of games in Europe are coming right at the end of their season, so it is always an interesting dynamic how to balance that."