Max Verstappen has conceded a "question mark" hangs over the United States Grand Prix Sprint given the lack of representative running through practice.
Teams have been given an operational headache with just one practice session before qualifying on Friday, with parc fermé imposed after just an hour of running.
Red Bull driver Verstappen had seen his fastest effort in qualifying taken away from him for exceeding track limits to leave him sixth on the grid for Sunday's Grand Prix, but the three-time World Champion rebounded to take the top-spot in Sprint Shootout.
"We were competitive but the last lap wasn't particularly great, but we are still on pole so it means the car is working well," said Verstappen.
"It is going to be an exciting afternoon with a lot of different cars being close to each other so you don't really know what's going to happen in the Sprint.
"It is all going to be a bit of a question mark.
"We are normally ok in races but this track is quite demanding."
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No Qatar repeat
Drivers will face the same lap count as the Qatar Grand Prix Sprint two weeks ago, where they struggled against the physical challenge of flat-out racing and the extreme conditions.
Ambient temperatures are similar in Austin this weekend, although humidity is down, and asked whether similar concerns could hit in the Sprint, Verstappen explained: "Tyre management is always quite key here, the wear is always quite high because of the high-speed corners and then you have to deal with the lower speed where you need traction.
"It is going to be tough, it is not going to be 19 laps of full throttle."