The Spaniard has raced for multiple F1 teams from Toro Rosso to McLaren, but neither have yielded the dream championship bid all drivers aspire towards.
Much has been written about his move to Williams, which in its current state, is undoubtedly a downgrade for Sainz.
But what if it isn’t?
What if Williams manage to achieve what they have been threatening to ever since they dropped to the back-row of the grid, and build a car that is capable of fighting at the front.
The 2026 regulation changes are a unique opportunity for the team to capitalise on this shake-up, and it could provide a championship winning car for Sainz.
After all, if anyone has proved that taking a gamble can materialise into title winning success, it is the man who is replacing Sainz - Lewis Hamilton.
Lewis Hamilton’s stroke of genius
In 2012 Lewis Hamilton made the shock decision to join Mercedes for the following season, leaving the far superior McLaren in a major gamble.
Approaching 30 and with one world title to his name, a dejected Hamilton was ready to take the leap to ensure further championship success.
At the time the press believed it was a mistake leaving McLaren, even his then team-mate Jenson Button was dubious of the decision.
However Hamilton's move was a stroke of genius, and following the 2014 regulation changes Mercedes came out on top after mastering the new engine rules.
Not only did Mercedes improve but they dominated F1 until 2021, with Hamilton claiming six back-to-back world titles in this period.
Sainz too will be moving to a team currently worse than the one he is leaving, but the star should look at Hamilton's career trajectory and allow it to inspire him.
Williams team bossJames Vowles has asserted that their path to the top of the grid will be a long one, and they do not expect instant results come the 2026 changes.
Sainz is aware of this and will be an integral part of their journey towards the front, and like Hamilton could join a team on the rise at the right time.
Despite these comparisons of age and career changes, there are several differences holding Sainz back from achieving this feat.
Firstly the nature of the Spaniard’s arrival at Williams diverges from Hamilton’s, who was swayed by the fresh challenge at Mercedes, and by F1 legend Niki Lauda’s passion for the project.
Alternatively, Sainz was dropped by Ferrari and left scrambling for a race seat at Mercedes or Red Bull, before being forced to look lower down the grid at Audi, Williams and Alpine.
When Hamilton moved to Mercedes he had already won a world title and multiple races, with years of experience fighting at the sharp end of the grid.
Whilst Sainz has raced in F1 for a decade he has not been consistently fighting for wins and championships, lacking the necessary experience for a title fight.
The Spaniard also lacks the speed and ability that the likes of Hamilton andMax Verstappen deliver consistently, meaning that even if Williams do improve, Sainz might not exceed what he has achieved at Ferrari.
Hamilton’s trajectory shows that not all is lost when Sainz moves to Williams, particularly if he can build a team around him.
The Ferrari star may be turning 30 but as Hamilton and even Fernando Alonso have shown, age bears little relation to success in F1, and Sainz still has more to give during the next phase of his career.
However, it could be a while before Williams are able to win championships again, and by the time they are ready, will Sainz be past his prime?
Whilst a championship bid would be the ideal birthday gift for Sainz when he joins Williams, he may struggle to convert it into a title with far superior talents racing on the grid.