Carlos Sainz made behind-closed doors Williams F1 debut today

Carlos Sainz made his debut for Williams today as part of a filming day ahead of the end-of-season F1 test in Abu Dhabi.

The Spaniard is joining Williams next year after making way at Ferrari so that seven-time world champion Lewis Hamilton can complete a blockbuster switch from Mercedes.

Ahead of Tuesday’s collective post-season test in Abu Dhabi, Sainz had his first run in the Williams FW46 around the Yas Marina Circuit.

Williams have opted to use their second and final filming day of the year to provide Sainz with an early opportunity to get a feel for their current car.

The run began at 4pm local time (12 noon GMT) and take place over a two-hour time slot.

As per F1’s strict regulations surrounding filming days, Sainz will be limited 200km of running - the equivalent of 38 laps around Abu Dhabi - using unspecified tyres provided by Pirelli.

This will simply provide an opportunity for Sainz to have extra time to bed himself in at Williams ahead of the official end-of-season test when he will also drive for his new team.

Sainz thinking about Williams on last laps

Sainz, who won two races for Ferrari in 2024, admitted he was already thinking about how he can help Williams improve their car in the final laps of Sunday’s finale in Abu Dhabi.

“I'm not going to lie, my last laps, as much as I was pushing like hell for this team and trying to, I was already starting to feel things in the car and trying to say, ‘remember how this feels’,” Sainz said.

“Because tomorrow and Tuesday I need to remember, why is this car quick in this corner and why does it feel good? Because I know probably what I'm going to find tomorrow, and Tuesday needs some margin of improvement in the corners that I was feeling the car. So this just sums up that I'm already looking also ahead.

“I'm extremely motivated for the challenge that I have ahead of me. Today is a day to try and enjoy as much as possible with the team as my last day in red.

“We still have some days in Maranello coming up, but obviously my competitive mind is already looking forward to Monday and Tuesday and to see how I can make that Williams car faster.”

No guarantee of next F1 podium

Sainz finished second ahead of teammate Charles Leclerc as Ferrari agonisingly missed out on the constructors’ championship to McLaren.

And he acknowledged he does not know when his next F1 podium will come.

“It's impossible to predict the future, impossible to know how long it's going to take me and Williams to be back fighting for podium positions,” he added.

“I think James [Vowles, Williams team principal] said it the other day and calmed everyone's expectations, that next year is going to be a tough year and a learning year before we prepare for the change of regulations in ‘26, where I believe the team is investing and the team is preparing to maximise that chance.

“What I can tell you is that I'm as determined as ever to help that team to be back where it belongs. I personally feel like I belong to be fighting for wins, podiums and top fives in Formula 1. I think I've proven it these last four years as a driver. I think I belong to that. But Williams cannot forget that Williams also belongs to fighting for these top five and podium places.

“And together with the determination and the strength that I think we're going to show together, the target is to get Williams and myself fighting for those positions in the near future, in the nearest future. How long that's going to take, I cannot tell you.”