Valentino Rossi found Laguna Seca tougher for his still-recovering leg and shoulder in Friday practice than the Sachsenring had been a week earlier, but remains confident that his condition will not hamper him.
The MotoGP champion made a spectacular return to action in Germany, just six weeks after breaking his leg in a Mugello practice crash, and with discomfort from his April shoulder injury still lingering. Rossi was around the top six all weekend at the Sachsenring, and finished fourth in the race - only losing third to Casey Stoner at the final corner.
Although he was sixth again in Friday practice in America, Rossi admitted the Laguna track had been harder on his body.
"This track is a bit harder for me than Sachsenring and I have more pain than I had there, mostly in the ankle but also in the shoulder at the braking point before the Corkscrew," he said.
But he is certain he can still be quick enough this weekend even if it is proving to be a stern physical challenge.
"Aside from that I think we can be better tomorrow," said Rossi. "We haven't put everything together yet to be at our full potential on the track and if we had a few more laps today we could have been a bit further up."