Hartley will be making his grand prix debut in the United States Grand Prix with the Faenza-based squad alongside Daniil Kvyat, who returns to the team after being replaced by Pierre Gasly in the previous two races.

Hartley was part of the Red Bull programme but was dropped in 2010 before going on to have a successful spell in the World Endurance Championship with Porsche, which signed him in 2014.

Ricciardo admitted he was "stoked" that his close friend has been given a second chance by Red Bull.

"We grew up pretty much together, and I think as far as racing mates go, I think he's probably the best mate I've had over the years," said Ricciardo.

"When I found out about it, I was super stoked for him. We are all competitors, but I feel like we've been through quite a bit, him in particular.

"He's been there and nearly fallen to the bottom, like racing old historic cars, just racing to race and race because he loved it. To get the Porsche drive was kind of big news, and to be back in this position was pretty huge."

He added: "It will probably sound like I'm a bit biased because I'm a friend, but as far as the older drivers go, he's deserving. He could have easily gone home to New Zealand after he got dropped, and just said, 'It's done, I tried, it didn't work,' but he's just ground away.

"His work ethic has been really impressive, and he's made it happen. I really believe he 100 percent deserves this opportunity, and now it's up him to then really take it to the next level."

Ricciardo revealed he knew that Hartley was back in the frame at Red Bull when he drove the simulator at the team's Milton Keynes base.

"When he went in the simulator the first time, it was: 'Don't say anything,' he said, 'I don't know what's going to come of it, but it's kind of cool that I'm relevant in their eyes at the moment'."

Ricciardo is confident that Hartley will do well this weekend, having already demonstrated his versatility.

"At the end of the day he's always been good, he's always been quick, and able to adapt really quickly. He's driven all kinds of cars the last few years.

"He won Petit Le Mans recently. So he's able to adapt, and I think it's really him, if he's got the confidence and calmness about him, then he'll be fine.

"He'll figure it out as well. For sure, if he asks me a thing or two, I'd be happy to give him encouragement."