Marc Marquez reasserted his mastery of the Circuit of the Americas on Sunday, winning MotoGP's Grand Prix of the Americas for the seventh time.

Marquez, starting third on the grid, seized the lead at the start and relentlessly powered to victory over championship leader Fabio Quartararo of France.

Marquez never allowed Quartararo a look-in, but the Yamaha rider pushed his lead in the standings to 52 points over Italian Ducati rider Francesco Bagnaia, who finished third.

With just three races left this season -- and with 25 points on offer to the winner of each one -- Quartararo is within touching distance of a first MotoGP world title.

"The plan exactly was like I did the race," said a beaming Marquez, the six-time world champion who won the first six races held at the Austin, Texas, circuit but fell off while leading in 2019.

The event was cancelled last season when he was recuperating after breaking his right arm in a crash, and his front-row start was his first since his return to the sport.

"Start well, be first in the first corner, be slow the first two laps and then when the tires drop a little bit start to push," the Honda rider said of the pre-race plan.

"That's exactly what I did."

By the halfway stage he was more than two seconds up on Quartararo, who started from the middle of the front row and finished 4.679sec behind.

Bagnaia, starting from pole for the third straight race, was running fourth with a few laps remaining, when his pressure on Jorge Martin finally caused the rookie to cut two corners and draw a long-lap penalty that secured Bagnaia's place on the podium.

Quartararo will have the chance to become France's first MotoGP world champion at the next race at Misano in Italy on October 24.

"It's so good!," said 22-year-old Quartararo.

"Physically it was very hard but it's great to see our result and to be in front of 'Pecco' (Bagnaia). I'm so happy to have increased my advantage."

Sweltering 33-degree C weather and a bumpy track surface that sparked complaints early in the week made for a demanding day.

The red flag came out twice during a crash-marred Moto 3 event, and while there were no serious incidents during the MotoGP race it was a punishing affair.

'Everyone happy'

Bagnaia, who had slipped back to sixth at the halfway point, was delighted to find himself among the top three.

"This podium is the best possible result," he said. "I gave everything. It was even harder than Malaysia! That was also hot but this track is more demanding. I have nothing left."

Marquez, however, made it look easy as he gave Honda their 450th top-class podium, and took another step in his return from injury.

The Spaniard had notched his first victory in 19 months when he won the German Grand Prix in June, saying at the time that since a third surgery everything was "more normal" but that he continued to have limitations.

A victory on a track where he has been a force was a positive note in a season of uncertainty, Marquez said.

"Sometimes I crash and I don't understand (why), sometimes I am slow and I don't understand, sometimes I am fast and I don't understand," he said.

"That special feeling still is not there with the bike."

Nevertheless, victory was an achievement worth celebrating.

"Today, everyone on the podium is happy," Marquez said. "Me for the victory, Fabio for second place. Maybe not 'Pecco', but I'm sure he'll be strong again in Misano."