Jenson Button EXCLUSIVE on the key to Williams convincing Carlos Sainz

2009 F1 World Champion Jenson Button says Carlos Sainz’s arrival at Williams shows you where he thinks the British team is going to be in the future.

Sainz left Ferrari at the end of the season, with Lewis Hamilton moving to the Scuderia to partner with Charles Leclerc from 2025.

But, while the Spaniard won’t win races immediately with Williams, Button says he’s made a calculated, smart move for 2026 – with the team focused on making a step change into the sport’s new era.

Carlos Sainz to swap Ferrari for Williams

“The regulation change is a big thing for the team, and it's what the team needs to really progress to the next step and I think Carlos can see that,” Button says, exclusively to Crash.net.

“He really does believe in the team, which is led James Vowles, and the important thing is James speaks the truth – and that’s why Carlos is interested to come to a team that isn’t winning races and to have the belief that he can be competitive in the future.”

Sainz is set for two early tastes of the Williams FW46 - first at the squad's second filming day, which will be held on the Monday after the season-ending Abu Dhabi Grand Prix, then again the following day at the postseason test.

Button, who remains an ambassador for Williams, alongside his other racing and media roles, is also excited for Sainz’s match-up with Alex Albon, who has proven to be a leading light for Grove since joining in 2022.

“It’s great for the team having Alex and Carlos; they have so much experience in the sport and have worked with some of the best teams in the world,” he says.

Williams driver conundrum with Franco Colapinto

Williams' driver decisions have been at the forefront of F1 all year.

The under-performing Logan Sargeant was axed at the mid-way stage, a show of team boss' James Vowles ruthlessness and eagerness to improve.

Franco Colapinto, who was previously largely unheralded, stepped into Sargeant's car and has impressed.

It brought the spotlight onto Williams' decision to pair Albon with Sainz in 2025, meaning they have no room for Colapinto.

Vowles has insisted that Colapinto's form warrants a full-time race seat next year.

Red Bull admitted they enquired about his availability, although Colapinto's previously red-hot form has cooled.

He was 18th in Saturday's sprint in Qatar.

Alpine have also been credited with an interest in Colapinto despite naming Jack Doohan as their 2025 driver alongside Pierre Gasly.

Colapinto's future is up for grabs - but Sainz is certainly not, after Williams completed the major coup to nab his signature.