Pierre Gasly says he was wearing only his underwear when he found out he will drive for Red Bull next year.
The Frenchman, who is in his first Formula 1 season with Red Bull's junior team Torro Rosso, will replace Daniel Ricciardo when he leaves for Renault.
Gasly, 22, received a phone call from Red Bull advisor Helmut Marko to confirm he will race alongside Max Verstappen.
"When Helmut called I was in my underwear," Gasly told Red Bull Racing.
"He said, 'Just to let you know we've made our decision and we'd like you to race alongside Max'.
"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 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 1 for this team."
Gasly, who made his F1 debut in the Malaysian Grand Prix last October, has scored 26 points for Toro Rosso this season.
He and Verstappen, 20, first met in the Red Bull junior driver programme.