Red Bull team principal Christian Horner insisted Max Verstappen is not available to fill Mercedes' vacant seat for 2025, having watched the world champion finish second to Lando Norris in first practice at the Dutch Grand Prix. (More Motorsport News)
Verstappen has dominated Formula One since beating Lewis Hamilton to his maiden drivers' championship in 2021, winning a further two titles and topping the standings again this year.
However, the Dutchman has struggled of late amid rumours his future could lie elsewhere, failing to win any of his last four races – his longest drought since an 11-race run in 2020.
With Hamilton agreeing to join Ferrari for 2025, Mercedes are one of just three teams yet to finalise their driver pairings for next season.
They were strongly linked with a move for Carlos Sainz, but he will join Williams next year after being displaced by Hamilton at Ferrari.
Mercedes have repeatedly refused to rule out an ambitious move for Verstappen, and ahead of taking part in his 200th race this weekend, the Dutchman suggested he will not remain in F1 for another 200 outings.
Horner, though, says there is no chance of Verstappen joining the Silver Arrows next year.
"It's just like we've been stating all the way through the year: we know what our agreement is with Max and Max knows what his agreement with us is," he told Sky Sports.
"He's certainly not available to Mercedes for 2025, he never was.
"I'm sure whatever options they choose to take, they've thought carefully about. If they choose to give [Kimi] Antonelli the seat, you have to commend them for taking a risk with a youngster."
Verstappen fell narrowly short of topping the timesheets in FP1 on Friday, as high winds and rain produced difficult conditions upon his Zandvoort homecoming.
McLaren's Norris beat Verstappen by two tenths of a second with a fastest time of 1:12:322, after the inclement weather resulted in limited running for the first 30 minutes.
Hamilton was third ahead of Sainz, with Mercedes' George Russell fifth-fastest and Williams' Alex Albon sixth.
