Rossi happy with second in practice

Rossi lies 20 points ahead of Stoner in the championship, but Stoner is in a rich vein of form coming into the US GP on a three race winning streak.

The Italian is hoping to close the 0.9-second gap between his Yamaha and the Ducati in first practice to allow him to fight for victory on Sunday.

"It was a good first practice for us, I did a good time and I think we have the potential to do better," said Rossi. "Second place is a good start, but of course we have work to do to catch Stoner who is faster than us.

"On some parts of the track we are good, but on others we lose our advantage so we have to improve the setting to be closer.

"In the Corkscrew I'm quite fast, but we're losing time down the hill after that, in the left, the right, and the last corner. I have some problems with turning to take the apex, and exiting the last corner we have to work on the electronics so I can open the throttle easier."

Rossi explained that the the low temperature, just 15 degrees celsius, made it more difficult to work on the set-up of the bike for race conditions.

"It was very cold this morning and in the first 20 minutes of the session it was very cold for the tyres," he said. "At the end it was better and we're expecting to go better with more temperature. As it gets hotter the bike gets easier to understand and to control.

"But it's been positive so far, it's good."