USA face England in their opening game of the World Cup in South Africa.
“Rooney is a top player. In my opinion, he is one of the best players in the world right now,” Donovan told Sky Sports News.
“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.”
