Mercedes Motorsport boss Toto Wolff has admitted the "relief is huge" within the Brackley team after Lewis Hamilton's fourth Formula 1 championship in Mexico also secured four consecutive double championship triumphs for the German manufacturer.

A ninth place for the Briton was sufficient on Sunday as contact caused by Sebastian Vettel in the opening few corners dropped both drivers to the back of the field after pit-stops for repairs.

But needing at least a second place to have any chance of continuing the battle to Brazil, the Ferrari driver could only manage fourth ensuring Hamilton added the Drivers' title to the Constructors' crown Mercedes won a week earlier in Austin.

"The relief is huge,” Wolff said. “During the race, you have mixed feelings, it's bittersweet because you're not where you should be. You could lose it and then it drags to Sao Paulo. It's a big relief now."

The Austrian was also critical of the actions of Vettel which saw him puncture the right-rear tyre on Hamilton's car while also damage his front wing. Indeed, he claims only the circumstances of the contact didn't result in the 30-year-old being penalised.

“I hated every bit of that race. It was really bad and too long and I think we were rattled after the beginning, after the crash," he claimed. "The championship is at stake and I think in normal conditions there would have been a penalty but it's the final race and the [title] decider."

Wolff also claimed it backed up Mercedes' approach of not backing off and assuming the championship was won.

"You have this massive gap in points and people say 'it's done' but it's not. It's motor racing and then you have this incident and Sebastian could have won and we could have not finished,” he said.

"Max knew there was so much at stake for the other two. For Lewis and Sebastian it's extremely difficult because you have to win the race and if you bail out of everything then it's not what we are here for.”

Now that the job is done, however, Toto can reflect on what his team has done and, doing just that, he believes the changes in the rules and competition made 2017 the most difficult of the four championship winning years.

“It was certainly, for the team, it was the hardest because we had quite some ups and downs, new car, new tyres and to accept that this is the reality now and to progress was very difficult for the team, it really took the maximum out of us,” he explained.

"Ferrari put the level up a lot and then Red Bull came into the game as well, as a team you are always in a more comfortable situation when you know that it’s one of the two that’s going to win the championship and trying to manage the inter-team rivalry was not easy at times but far away from the struggles of this year.”