Christian Horner has ruled out a return to the Red Bull Formula 1 team for Sebastian Vettel, believing an "alpha male" partnership with Max Verstappen would not work.
Vettel made his name with Red Bull, initially with a season and a half with Toro Rosso before being promoted to Red Bull in 2009, going on to win his four world titles from 2010-13.
Without a drive for 2021 after recently announcing he is to leave Ferrari at the end of this year, there appear to be few options on the table for the 32-year-old German.
Team boss Horner claims he is "happy" with his current driver line-up of Verstappen and Alex Albon going into next season.
"I think it's enormously unlikely," Horner said on Sky Sports News when asked about the likelihood of Vettel returning to Red Bull.
"We have a long-term agreement with Max. Alex is doing a good job. We've got a good dynamic within the team.
"Experience shows that two alpha males, it doesn't tend to pan out well. I don't think it would be conducive for our team to have two alphas."
Although Horner feels Vettel is "not short of options", he has not ruled out the possibility of him retiring.
"That ultimately is his choice," added Horner.
"He's still relatively young, he's in his early 30s. If he chose to stay, he's obviously still very competitive.
"That's entirely down to him, and nobody will know that apart from Sebastian what his choices are.
"He's got strong values, he's got strong integrity, and I'm sure he will have thought long and hard about this.
"Whether he chooses to continue or not, he's achieved a huge amount during his time in F1.
"Four world championships, he's one of the most successful drivers of all-time."
Before you go...
Ricciardo backed to take McLaren "to the next level"
Is Alonso again willing to dedicate his life to Formula 1?
Related