Lewis Hamilton said his fightback from first-lap contact to finish ninth in Sunday's Mexican Grand Prix was "a horrible way" to clinch his fourth Formula 1 world championship, having been unaware of the title permutations during the race.

Hamilton dropped to last after contact with title rival Sebastian Vettel at Turn 3 left the Mercedes driver with a left-rear puncture, leaving him to fight his way back up the order through the race with a chunk of his rear diffuser missing.

With Vettel also falling back and only finishing fourth, Hamilton was confirmed as world champion at the chequered flag, but admitted he felt uncomfortable throughout the race.

"It was a horrible way to do it to be honest! But what could I do?" Hamilton said.

"I told you I wasn't going to go easy at Turn 1, and I don't think I was too aggressive or anything like that. I placed my car in just the perfect position. I'm looking forward to seeing the replay, but I left a lot of space for the car behind. I kept going and I kept coming back.

"I've got to say a big thank you to all the guys at Brixworth and Brackley. Guys, thank you all so much for all your hard work. Winning the constructors' championship this year was already a huge feat, and helping me achieve this incredible accomplishment, I'm so grateful."

Hamilton continually asked his Mercedes engineer about the title permutations throughout the race, and admitted he was never fully aware of if the title would be decided.

"Today was the most unusual [race]. Being 40 seconds behind is horrible, it's like being in No Man's Land, but you just have to keep thinking forwards to the future," Hamilton said.

"I had no idea what was going to happen in the championship to be honest, I was just thinking about getting further up and catching and getting involved in the race. This is such a difficult track, if not the worst track to follow. So trying to get past people was a disaster.

"To be honest, I guess the feelings are so mixed right now. And then I ran the last part of the track so I'm a bit thirsty..."

When asked how many titles would be enough for him, Hamilton said: "I just kind of think you should take it one day at a time. I'm really happy with this fourth. I'm really going to have take some time to really think about it.

"I'm proud of the flag and everyone that represents it, and that those who are watching are happy with this year's result, and I'll continue to rise it as high as I can."