MotoGP champion Marc Marquez admitted that his wild high-speed moments over the Austin circuit's bumps on Saturday put pressure on his long-standing shoulder injury.
Marquez had surgery on the problem in December and was adamant it would compromise his fitness in the early part of this season - although that has not stopped him finishing second and first in the opening rounds, and then taking pole for this weekend's Grand Prix of the Americas.
On Saturday he had two massive moments on the bumps that had prompted significant criticism from riders during Austin practice.
When asked if he felt any pain during those incidents, Marquez replied: "Yes, I would be lying if I said no.
"I'm very happy I arrived at a good level with my shoulder because on this track I feel it - especially in the shaking.
"In the change of direction, it's not so bad, the power is there, but with the shaking I feel it a little bit.
"In Argentina I was able to forget about it completely, but here I come back to using the ice and the physio.
"Luckily for me there was no riding in FP3, and FP4 was easy. My physical condition will be fit [for the race]."
Despite his pace advantage at Austin, where he has never been beaten to a pole or race win in MotoGP, Marquez insisted his Honda is not as good at absorbing the bumps as some rivals.
"Valentino [Rossi] says it's one of the strongest points of the Yamaha, but the bumps are one of our weak points," said Marquez.
"We are trying to analyse why. Of course, the set-up we have on the bike, and especially the electronics, is to ride without wind under the front wheel and [in qualifying] it was really windy there.
"It was shaking, and there was even some water there, but it was shaking a lot. I believe in the race it will be less windy.
"[In qualifying] even on the fastest lap I couldn't be full [throttle], I was just closing a little to be safe.
"With the second tyre I tried to be full, but it was shaking too much.
"If it's too windy we will change the set-up but if not we will stay with this one."