Lewis Hamilton stands on the verge of being crowned a four-time Formula One world champion in Mexico City this weekend, but Sebastian Vettel has not given up hope of denying the Briton.
Championship leader Hamilton extended his advantage over Vettel to 66 points last time out in Austin and will secure a fourth title with a fifth-place finish or better at the Mexican Grand Prix - even if the German wins the race.
Since the mid-season break, the Mercedes driver has been in sensational form, collecting 143 points out of a possible 150, while Vettel has encountered reliability problems in his Ferrari.
Hamilton is determined to finish the job with a 10th win of the season at the Autodromo Hermanos Rodriguez, but Vettel will continue to fight until it is mathematically impossible to catch his rival.
"It's not over, though obviously it's not in our hands as much as we'd like it to be," Vettel said ahead of Sunday's race. "The pity really is that there were a couple of races where we just weren't there to fight. We didn't have a chance to fight.
"They obviously got away from us and we were just sitting on the sidelines. That was bitter but in the end, made a big difference.
"Nevertheless, we are now where we are and, as I said, we still have a chance.
"We want to win the last three races and I think we can. So that's our goal. And then we see what happens."
Should Hamilton seal the title on Sunday he will join Vettel and Alain Prost as a four-time world champion, with only Juan Manuel Fangio (five) and Michael Schumacher (seven) ahead of him.
WHAT WE LEARNED FROM PRACTICE
After Mercedes topped the timesheets in Friday's opening practice session, Valtteri Bottas proving quicker than Hamilton, FP2 provided plenty of intrigue and uncomfortable moments for the Silver Arrows duo.
It was Red Bull who displayed the most impressive long-run pace in the afternoon. Daniel Ricciardo posted the fastest lap time, while team-mate Max Verstappen was third behind Hamilton as the Ferraris of Vettel and Kimi Raikkonen followed in fourth and fifth.
Hamilton endured a scare when he lost control of his car and spun early in the second session, while Vettel suffered an unusual setback as his car's fire extinguisher went off in the cockpit to cause significant discomfort.
"Initially it was just burning but it turned out to be very cold. I had to go back and we changed it and lost some time," Vettel was quoted as saying by BBC Sport.
Friday also brought confirmation of hefty grid penalties for McLaren drivers Fernando Alonso and Stoffel Vandoorne, who will therefore start from the back of the grid on Sunday. Toro Rosso's Pierre Gasly faces a five-place penalty for using a fifth control electronics unit.
1. Lewis Hamilton (Mercedes) - 331
2. Sebastian Vettel (Ferrari) - 265 (-66)
3. Valtteri Bottas (Mercedes) - 244 (-87)
4. Daniel Ricciardo (Red Bull) - 192 (-139)
5. Kimi Raikkonen (Ferrari) - 163 (-168)
1. Mercedes - 575 (champions)
2. Ferrari - 428 (-147)
3. Red Bull - 315 (-260)
4. Force India - 159 (-416)
5. Williams - 68 (-507)
2016: Lewis Hamilton
2015: Nico Rosberg
It will be warm and sunny in Mexico City for much of the weekend, which bodes well for Hamilton, and even the cloud forecast on race day appears unlikely to hold the Mercedes back.