Pierre Gasly was in his underwear when told of Red Bull promotion

Hockenheim hot lap with Lando Norris (2:20)

ESPN's Laurence Edmondson takes a hot lap with McLaren test and reserve driver Lando Norris around the Hockenheim circuit. (2:20)

Pierre Gasly was caught slightly unawares by the call from Helmut Marko saying he would be promoted from Toro Rosso to Red Bull next season.

The French driver will make the step up to replace Daniel Ricciardo, who is making a shock switch to Renault for 2019. As one of two existing Red Bull junior drivers Gasly's elevation seemed to be a formality as soon as McLaren confirmed the signing of Carlos Sainz last week.

Despite that, when the confirmation finally came from Red Bull motorsport advisor Marko, the head of the company's driver programme, Gasly was not even fully dressed.

"When Helmut started the call with me I was in my underwear," Gasly told Red Bull's official website. "When the call ended I ran around the house shouting to my mates and they all jumped in the pool straight away!

"There was so much excitement and I was so happy about it because it's something I've wanted for a long time. Of course when I came in to the Red Bull Junior programme that was the target, to drive in Formula One for this team, so I was just so so happy and had so much excitement."

By partnering Max Verstappen, Gasly goes against one of the grid's most hyped young talents. Verstappen became F1's youngest race winner at the 2016 Spanish Grand Prix and has since added three more victories to his name, including this year's Austrian Grand Prix at Red Bull's home race.

Gasly is relishing the prospect of competing alongside the Dutchman. .

"Being teammates and mates with Max next season is really cool, because we get on really well and we've known each other for a really long time. We used to race against each other in karting in 2010 as a junior, so we've already raced together, but not for the same team. We've actually had a couple of close battles, sometimes good for me, sometimes not so good, but we really enjoyed that time.

"We really respect each other a lot as drivers, but also as friends, so I'm really excited to join him in the team with him. As we have a strong friendship it will be only a positive for the team."