Bolton and USA midfielder Stuart Holden has identified Manchester United striker Wayne Rooney as England's key ahead of the World Cup clash between the two nations.

The USA meet England in Rustenburg on Saturday in their opening Group C match and Holden sees Rooney as the most important player in the English squad.

This week, Rooney reportedly lost his cool during a warm-up match and some media outlets have suggested the USA target this but Holden said it is just part and parcel of the game.

"I think Rooney's a world-class player, and the way he plays is that he leaves everything on the field," Holden said. "That's a testament to the player he is, in that he's so competitive and he wants to win so bad that he loses his temper a little bit.

"But that's a part of football, and I think there are other footballers out there that play with that same type of passion and leave everything out on the field."