Austin's Circuit of the Americas is "in really good shape" everywhere except one spot at Turn 1, according to the venue owner, following a suggestion from Max Verstappen that the circuit's bumpy surface might cause him spine damage.

Verstappen said ahead of this weekend's U.S. Grand Prix that COTA's bumpiness has grown "out of control" in recent years, citing a recent World Endurance Championship (WEC) race he watched as well as his own experience from previous seasons.

The Red Bull driver said a check-up of his lower spine showed some damage from the wear and tear of racing.

Reigning world champion Lando Norris backed up Verstappen's concerns, saying he's previously needed headache tablets for the bumpiness he's experienced inside the cockpit at COTA.

Circuit boss Bobby Epstein is confident the situation will not be as extreme as the two drivers predicted, with work done this year to flatten out the tarmac in key areas.

"We don't feel good that there's a bump at the bottom of Turn 1," Epstein told ESPN. "We didn't know about it until this week. We would have fixed it.

"But the other things Max spoke about, all the bumps around the track, we've fixed them. The track is in really good shape.

"I talked to some WEC drivers who said there's no problem. There's one bump at the beginning of [Turn] 1 that is not acceptable in my mind ... It's a dip, not a bump. If it were a bump, we'd sharpen it out, we'd take care of it tomorrow night, or overnight tonight, and that kind of stuff's happened before [at other circuits]. But when it's a dip it's a lot different, there's no easy fix."

- Ferrari's Charles Leclerc sets pace in second practice from Kimi Antonelli at United States Grand Prix
- FIA president hints at long-awaited F1 V8 engine return: 'Watch this space'
- Carlos Sainz on F1 season concluding in Middle East: 'Very difficult to be convinced right now'

Speaking between Friday's two practice sessions, Epstein joked that he had no doubt Verstappen would agree with him after driving on the track.

"Max doesn't say I'm wrong a lot, but he's also right a lot, and he's usually very frank, and I appreciate that about him," Epstein said. "I had no problem with him saying what he said. I think he might be surprised in some areas that bumps he thought were here aren't any more."

Verstappen did not give his opinion after practice -- teams are only required to send one of their two drivers to talk to the media on Fridays, and Isack Hadjar went.

Cadillac's Valtteri Bottas appeared to agree that the circuit has improved from last year.

"They've managed to grind some of the bigger bumps, but it is a fun track," Bottas said, although other drivers suggested the extreme bumpiness has remained.

Alpine's Franco Colapinto was one of them.

"It's a great track to drive at," the Argentine said. "For the drivers to drive F1 around these high-speed corners, it's one of the best tracks in the world. It's a pity that it's so bumpy, because it becomes harsh on the body as well, our backs suffer. It's not the easiest. Hopefully they can improve it for the future."