Jean-Eric Vergne says he is no longer friends with his Toro Rosso teammate.
Until they were paired together at the second Red Bull team, Frenchman Vergne and Australian Daniel Ricciardo were friends.
They had been signed to the energy drink company's notoriously tough driver development programme on the same day, thereafter working together in Formula Renault.
But now in the high-stakes world of F1, and fighting for a place at the world championship team, the friendship has ended.
"I don't know if it's because we are in F1 or he (Ricciardo) thinks he has definitely beaten me that we cannot have any relationship, but, no, we don't see each other away from the track and we are not friends," Vergne is quoted by the Melbourne newspaper The Age.
Vergne insisted, however, that their working relationship is intact.
"I don't care about going on holiday with my teammate. I have my friends and I don't need any more," he added.
Ricciardo, who is almost a year older than Vergne, confirmed that the close friendship of the past is over.
"We've never come to blows or anything like that," he said. "There's never been a moment which has separated the friendship -- it's just grown apart with competition.
"I imagine we're probably like most other teammates. I think it's how it should be.
"I think when you're a direct rival with someone, you want to have your own space.
"I think it would be sort of hard to have a true friendship because, at the end of the day, we're fighting for maybe one spot and there can't be any conservative approach about it," added 23-year-old Ricciardo.