Lewis Hamilton says his fourth Formula One world championship was the hardest to win, after beating Sebastian Vettel to the title at the Mexican Grand Prix.
Pole sitter Vettel needed to win the race with Hamilton lower than fifth in order to keep his slim title chances alive until the penultimate race of the season in Brazil, but contact between the pair in the opening sequence of corners forced both drivers to make an early pit stop to repair respective damage to their cars.
Vettel pulled off a charging recovery drive to finish fourth, while Hamilton crossed the line in a low-key ninth, a result which proved enough for the Briton to seal his fourth F1 title, moving him level with Vettel and alongside Michael Schumacher, Juan Manuel Fangio, and Alain Prost as the only drivers to have won at least four world championships.
2017 has marked the first season two F1 teams have battled for the drivers' championship since 2013, as well as being the first occasion Hamilton and Vettel have gone head-to-head in a direct fight for a championship, despite taking seven of the last eight titles between them.
"I definitely think this has been [the hardest]," Hamilton explained. "2008 was tough, 2007 was difficult [Hamilton missed out on the title by a single point]. 2008 was very tough. The following years have just been different.
"This year, being in a position to really lead the team and help drive, motivate and direct the car exactly where I want it to go in its development, alongside a great team-mate and fighting against a great team in Ferrari with the highest decorated, or was the highest decorated driver in the sport -- we are now both -- was a massive challenge I was looking forward to."
Despite facing a significant challenge from a rejuvenated Ferrari in 2017, Mercedes was able to claim its fourth consecutive constructors' world championship with three races to spare at the U.S. Grand Prix. Hamilton said Mercedes' intense fight with the Scuderia in both world championships prompted the whole team to raise its game.
"It's great to have two teams fighting. You could see through practice [in Mexico], us all within a tenth, the top six or whatever. I think that's great. We need more of that. It pushes us all more to the limit, it pushes the cars more to the limit and that's ultimately what has got us excited for the sport.
"We've all loved that challenge. Every single individual in the team has really raised their game. You go to the factory and I'm like 'why are you still here at 7pm or 8pm?' Sometimes it's later. They are like 'I've got a championship to win'. That hasn't come so easy."