Rookie Toro Rosso racer Brendon Hartley admitted Thursday that his chance to race in this weekend’s United States Grand Prix had come "out of the blue".

But the 27-year-old New Zealander said that, seven years after being dumped by the Red Bull stable, he was returning as a much stronger and fully-rounded driver than before.

“When I spoke to people about going back, I always said it was unrealistic, but the dream was always there,” he said.

“But honestly, at 27, when the age of the drivers is starting to get lower and lower, I wasn't sure.

"They are obviously taking a chance with me and they have obviously done their homework.

“I’m a much stronger and more rounded driver now. I went through some tough times. Mentally I'm much stronger now. I don't make nearly so many mistakes. I am more prepared than ever as a racing driver."

Hartley’s surprise call-up came after the team released Carlos Sainz to join Renault and Pierre Gasly to race in Japan.

Red Bull supported Hartley’s single-seater career in Formula Renault and the British Formula Three championship before dropping him in 2010.

He switched to sports cars and joined Porsche, taking part in this year’s victory at the Le Mans 24-Hours race.

He said he phoned Red Bull’s Helmut Marko to inquire about a possible drive “if ever there was an opportunity.”

“He got the message and this came up at the last minute -– and quite out of the blue.”

Source: AFP