England coach Brian Ashton was unable to explain his side's lacklustre performance after they struggled to a 28-10 victory over the USA.

A near full-strength England side managed just three tries against the Eagles, a team of mostly amateur players, and left Ashton (pictured) with few crumbs of comfort ahead of the crucial Pool A clash with South Africa.

England scored tries through Jason Robinson, Olly Barkley, the one positive from the game, and Tom Rees.

But their superior fitness and experience failed to tell in the second half and it was the Americans who finished the stronger.

"We've made a winning start but it was less than a satisfactory performance," admitted Ashton.

"There was a lack of physicality and energy but I've no idea why - I can't put my finger on it.

"I thought we'd kick on after we scored the third try but suddenly we started having problems at the line-out and you can't build your game," added Ashton.

"The last 20 minutes were very disappointing from out point of view, without taking anything away from the USA who hung on until the end."

Skipper Phil Vickery, who was disappointed and taken off in the second half, was also at a loss to explain the performance, though he did at least try to see the positive side of getting off to a winning start.

"I am delighted with the win but disappointed with the performance," said Vickery.

"The USA made it made it difficult as we knew they would.

"What was it down to? Nerves, opening game, a lot of hype in the papers but you've got to be a little careful as emotions do run high after a match.

"We are not going to over-react but we know we didn't play very well."

England face South Africa in Paris on Friday and must also play Samoa and Tonga to get through their pool.

Terence O'Rorke / Eurosport