Hartley joins Toro Rosso for Austin F1 race

The Kiwi racer has been drafted in as replacement for Frenchman Pierre Gasly, who will be competing in the Super Formula finale in Japan instead.

With Hartley having fallen off the F1 radar in recent years as he focused on sportscars, the call-up is a big shock.

"What an amazing feeling,” said the 27-year-old. “This opportunity came as somewhat of a surprise, but I never did give up on my ambition and childhood dream to reach F1.

“I have grown and learnt so much since the days when I was the Red Bull and Toro Rosso reserve driver, and the tough years I went through made me stronger and even more determined.

“COTA is a track I really enjoy and one I have raced at recently. I'm trying not to put too many expectations on my F1 debut, but I feel ready for it."

Hartley is no stranger to Toro Rosso, having tested for the team back in 2009. As a former Red Bull junior driver, he was also test and reserve driver for the energy drinks company’s two teams that year and 2010.

However, he was dropped by Red Bull soon after – and his most recent F1 running was with Mercedes in a test at Magny-Cours in France in 2012.

Most recently he has focused on sportscars, competing with Porsche in WEC and winning the 2015 championship alongside Mark Webber and Timo Bernhard, as well as this year's Le Mans 24 Hours.

Toro Rosso team boss Franz Tost said that Hartley's recent driving experiences, and success, has prompted him to become top choice to step in for Gasly.

“Brendon is coming as the reigning Le Mans 24 Hours winner and he's also leading the current FIA World Endurance Championship, which he won in 2015 as well,” said Tost.

“We are really happy to have him back in our team. With all the racing experience accumulated over the years, we are convinced that he will do a fantastic job for us."