Max Verstappen "won't be" at Red Bull at the start of the 2026 Formula 1 season, amid ongoing rumours linking him to a potential move to Mercedes.

That is the opinion of former Red Bull driver Robert Doornbos, who believes it will "be difficult" for the team to convince the newly crowned four-time World Champion to stay beyond next season.

Verstappen clinched a fourth consecutive title at last weekend's Las Vegas Grand Prix, cementing his place alongside some of the greatest drivers in F1 history.

Despite being contracted to Red Bull until the end of the F1 2028 season, Verstappen has been consistently linked with a move away from the team throughout F1 2024 as a result of the competitive decline of the RB20 car and the tensions between his father Jos Verstappen and Red Bull team principal Christian Horner.

Mercedes boss Toto Wolff made no secret of his desire to sign Verstappen for F1 2025 before deciding on teenage sensation Andrea Kimi Antonelli as Ferrari-bound Lewis Hamilton's successor.

With Mercedes opting against specifying the length of Antonelli's contract, however, and George Russell's deal expiring in 12 months' time, the team are expected to renew their interest in Verstappen ahead of the major F1 2026 rule changes, for which Mercedes' preparations are believed to be advanced.

Mercedes previously emerged as F1's dominant force at the start of the V6-hybrid engine era in 2014, after which the team won a record eight consecutive Constructors' titles and seven straight Drivers' crowns split between Hamilton (six) and Nico Rosberg (one).

Aston Martin, who will enter a works partnership with Red Bull's current engine suppliers Honda from F1 2026, have also been linked with an ambitious move for Verstappen following the capture of F1 design guru Adrian Newey.

Horner confirmed to media at August's Dutch Grand Prix that Verstappen's contract contains a "performance element" allowing him to leave the team before the end of his contract in 2028.

A report in the British media last month claimed Verstappen could trigger an exit clause in his contract next year if he is lower than third in the Drivers' Championship after a "significant part of the season" has been completed.

If true, this would echo an arrangement widely reported to have been included in one of Verstappen's previous Red Bull contracts.

However, Verstappen Sr insisted over the Las Vegas Grand Prix weekend that his son will see out the entirety of his current Red Bull contract, raising the possibility of a sabbatical at the end of F1 2028.

Verstappen himself has been publicly cool on a move away from Red Bull, recently claiming it is "definitely the intention" to stay with Red Bull.

Doornbos revealed in August that he expects Verstappen to join Mercedes for F1 2026, even though Aston Martin boss Lawrence Stroll is "sparing no expense" in his efforts to land the World Champion.

And he has reiterated his stance that Red Bull are set to lose Verstappen at the end of next season, with Mercedes' F1 2026 engine preparations likely to be pivotal to his decision.

Appearing on Crash in the Kitchen, Doornbos said: "It will be difficult for Christian to keep Max on board."

Put to him that Verstappen has publicly indicated a willingness to stay put at Red Bull, he said: "Did you expect him to say something different after winning a fourth world title?"

Doornbos believes a tricky title defence in F1 2025 is likely to convince Verstappen to move on, having been restricted to eight victories so far this season after setting a new record of 19 wins in a dominant F1 2023.

He added: "What more do you need to develop it (the car)? The regulations don't change. You can't expect to get a completely different concept car.

"Believe me now: in 2026, he won't be there."

"Lewis Hamilton did not have the best car aerodynamically and mechanically for seven years [at Mercedes]. They had a cannon of an engine. I think you need that in 2026."

Meanwhile, 2009 World Champion Jenson Button claimed that Verstappen will have no choice but to "think of number one" if Red Bull fail to provide him with a competitive car going forward.

Appearing on the Sky F1 podcast, he said: "He was asked after the race: if we start the F1 season like we've ended, does that put you guys in a really difficult position as a team?

"It will. You look at it and they're probably the third-best, if not fourth-best, team at the moment, so it is tricky.

"But then Max came back with: 'Yeah, but we haven't had the best car since the seventh or eighth race and they still haven't closed on me in the championship' – which is a good point.

"Maybe he's making more of the difference, but they're still able to get the maximum out of the car every weekend.

"Even though it's not a win, I think they're maximising what they have and I don't think the other teams are doing that as much. They're not maximising what they have on any given weekend.

"So as a team, they are still great. They just don't have the performance in the car like we've expected over the last three-and-a-half years.

"But if they start like they are now, it puts a lot of pressure on the drivers to really maximise every weekend. It's a tough one.

"Maybe he will look elsewhere, but they've given him so much over the last few years in terms of performance.

"It's always a tricky one for a driver. He doesn't want to leave a team that's given him so much, but he's got to think of number one, which is himself."

Verstappen has frequently warned over recent years that he will retire young, with the Dutchman frustrated by the commitments the expanding F1 calendar places on drivers.

Button is convinced that Verstappen will have no trouble succeeding elsewhere if he decided to exit the pinnacle of motorsport.

He added: "There's two different types of F1 driver.

"There's the F1 drivers that are F1 drivers and that's all that matters to them.

"When they step away from the sport, they won't race anymore. They'll go and sit on a beach somewhere or find another job that interests them.

"But for Max and others like myself, we love motor racing. It's not just Formula 1.

"So Max won't step away from winning, he'll step away from Formula 1. He'll go and race.

"He's talked about doing endurance racing – maybe Le Mans, Daytona. Maybe it'll just be sim racing, who knows?

"But he will still be there fighting for wins. That's not going to change. It's just that the environment will change.

"Formula 1 is the pinnacle, it really is. But there's a lot more pressures on your shoulders than in other categories and a lot more eyes on you.

"So who knows? Maybe this will be his last contract in Formula 1: he'll see out his contract with Red Bull and then he'll move away.

"Who knows? But he will be racing for a very long time, just maybe in a different capacity."