Valentino Rossi has described the condition of the Circuit of the Americas track as ‘critical’ after completing the first day of MotoGP free practice in Austin, Texas.

The Italian enjoyed a positive morning and afternoon, ending FP2 with the fourth fastest time, a place behind team-mate Maverick Viñales and two back of Marc Marquez.

But more than his feeling on his Yamaha M1, Rossi was more worried by the failure of the Circuit of the Americas to eradicate the bumps around the 3.4-mile track, with the back straight a particular cause for concern.

“First of all I like the track,” began Rossi, 0.359s slower than Andrea Iannone, the quickest of the field on Friday. “It's good to ride because it's very difficult, you have emotional corners, so it's good.

“But the situation of the bumps is critical, it's a disaster. For me, it's the worst situation of the whole season. Because you have three or four bumps which are very big, because with our bumps it's very difficult, because you have a lot of bumps in the straight.

“The bike moves very much at more than 300 km/h and it's a critical situation. Also the grip is not fantastic, but it looks like it improves practice by practice, but I'm more worried about the bumps.

“Last year we asked to do some improvements, they did something, but unfortunately it doesn't work. So the situation with the bumps is critical.”

Asked where he felt the bumps were most pronounced, Rossi said, “Turn two is very bad. turn ten, big bumps. And back straight, when you go up after the dip, you go over the crest in fifth and sixth, the bike moves a lot because there are big bumps, a lot of bumps in the braking also.

“And big, big bumps, maybe the biggest one is Turn 18, before the last two lefts, you touch the fairing on the ground, so it's like motocross. It's a shame, because personally I like this track very much, it's very good, but the bumps start to be a problem.”

Riders encountered the fairly unique situation on Friday morning of riding among clouds of dust when entering the back straight.

Commenting on this, Rossi said, “The situation was very strange, especially in the first practice, because it was like being at the ranch! So you have a lot of white and dust, and you don't see anything in front, and it's very strange.

“Maybe coming from the asphalt, but I don't know. But it's also true that it was better in the afternoon. But on the back straight, the situation is still bad.”

And does he feel the Yamaha is more affected by the bumps than other machines? “Boh… I don't know. I think every rider will say the other ones! I don't know sincerely, but we suffer a lot.”