Live blog: Brendon Hartley's Formula One debut at the USA GP

Brendon Hartley during a practice session at the US GP. Photo / AP

Live updates of the US Grand Prix in Austin, Texas, where Kiwi Brendon Hartley makes his Formula One debut for Toro Rosso.

Hartley will start from the back of the grid in this morning's US Grand Prix but his future with the Toro Rosso team looks bright.

The 27-year-old was a late call-up for the event at the Circuit of the Americas, replacing youngster Pierre Gasly for the one-off race, but team boss Franz Tost gave the strongest hint yet that the Le Mans 24-Hour champion is in line for an extended stay with the team.

Not only is he likely to race at next weekend's Mexican Grand Prix but a fulltime drive next year is now on the cards.

"If he shows the performance in the next few races and improves then I am convinced that he will become a driver for next year," Tost told Radio Sport. Asked whether Hartley will back up next week in Mexico, Tost all but guaranteed the New Zealander would get more chances to impress and secure a fulltime drive.

"I think so," he admitted. "We will have a conversation after Austin but it looks good he will drive for us in Mexico."

Gasly, who skipped today's race to contest the final round of the Asian Super Formula event in Japan, is almost certain to return to the team in Mexico leaving fulltime driver Daniil Kvyat vulnerable of missing out altogether.

While Kvyat out-qualified Hartley, he has struggled this season to the point where he was dropped for the past few Grands Prix while rookie Gasly was given an opportunity to establish himself in Formula 1.

Tost refused to comment on the Russian's future.

"Let's wait and see - it is not decided yet. It is open and it will be a decision from Red Bull."

Hartley did a solid job in qualifying - eventually setting the 18th fastest time in his first attempt in the category.