The Spaniard claimed pole with a time of 2:00.789, beating rookie Pedro Acosta by 0.328 seconds who was followed by Marc Marquez, last year's champion Francesco Bagnaia and Enea Bastianini.

"We are very confident. Every race, I feel stronger and stronger. I really like the Austin track, it's a circuit that really suits my driving," said Vinales, who won the Portuguese GP Sprint last month.

"We want to have a good race. The sprint race will be very tough but we're going to put on a good show."

Acosta said he was happy to have the second place in the starting grid.

"This weekend, for us it was important to see what we could do on a new circuit, and a fairly difficult circuit like this," he said.

"We'll see in the sprint, we've made changes since Portugal to fight for something. We'll give it a go."

Vinales' Aprilia teammate and championship leader Jorge Martin finished sixth after crashing twice. Brad Binder, second in the standings, came in 15th.

The sprint will be held later on Saturday.