Max Verstappen became Formula One world champion for the first time on Sunday after a thrilling end to a compelling season spread over nine months and 22 races.
It all came to a head with Verstappen's win in Abu Dhabi in a nail-biting last-lap contest with Lewis Hamilton.
The title chase went to the final race with the two drivers locked on the same number of points, the first time that had happened since 1974.
AFP Sport looks at five other key moments on the road to Abu Dhabi that marked out arguably the most memorable Formula One title fight of the 21st century.
After Lewis Hamilton had won the opening race in Bahrain, there was a sense of the inevitable about the season ahead: the Briton was surely on course for an eighth world title.
Imola changed that as Verstappen, starting in third, made a superb start. On a wet track, "Mad Max" flew out of the blocks, overtaking both his teammate Sergio Perez and Lewis Hamilton, on pole, to take the lead, and forcing Hamilton to take to the grass, which damaged his front wing.
Verstappen and Red Bull managed the race to perfection after that and although Hamilton recovered from ninth at one point to finish second, the champion knew he was in a title race.
Victory in France had given Verstappen an imposing 32-point lead in the championship but Hamilton hit back in the next race on home soil in dramatic fashion.
Verstappen was again on pole after winning the qualifying sprint race, the first of three to be trialled during the season, with Hamilton's Mercedes beside him.
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A first-lap battle for the lead resulted in a collision between the two which saw Verstappen careening into the tyre wall on turn nine at 290 km/h (180 mph).
Hamilton was given a 10-second stop penalty but with his rival out of the race, and having check-ups in hospital, went on to win the race. His celebrations did not go down well with Red Bull and the post-race recriminations set the tone for a war of words off the track that has echoed through the remainder of the campaign.
There was something about Italian tracks that triggered the 'crazy' in the title rivals -- and Monza would not disappoint.
The tone was set with a nudge between the two on the opening lap during which Daniel Ricciardo slipped ahead of Verstappen to take the lead.
Things cranked up a notch midway through when Hamilton emerged from the pits just in front of the Dutchman who bounced over a kerb, making contact with Hamilton's left rear tyre.
That launched Verstappen's car into the air in spectacular fashion and on top of Hamilton's car. The Briton was saved by his halo but both cars were out of the race, prompting further recriminations between the teams.
Max Verstappen went to Brazil on the back of wins in the US and Mexico and with a 19 point lead over Hamilton. Another victory would all but hand him the title.
But it was Hamilton who showed his championship. A technical infringement after qualifying first saw the Briton sent to the back of the grid for the sprint qualifier. Hamilton burned through the pack to finish fifth but received a further five-place grid penalty for exceeding his quota of internal combustion engines.
But in perhaps the most sensational performance from any driver in 2021, Hamilton, starting 10th on the grid, picked his way through the field, overtaking Verstappen to claim the win.
He was on target for the fastest lap as well until Red Bull pulled in Sergio Perez for a late change of tyres, a move that worked and deprived Hamilton of a vital point. "With the penalties, it's the hardest race weekend I've had," said Hamilton.
In one of the most chaotic races ever, which saw two restarts and numerous safety cars, Hamilton made it three wins in a row to draw level on points with Verstappen.
The inaugural Saudi Arabian GP, on the street circuit of Jeddah, was marked by an intense battle between the two leaders who traded the lead and tangled on the track when Hamilton ran into the back of the Dutchman who slowed after being ordered to allow the Englishman past following an illegal manoeuvre.
Verstappen was later hit with a five-second penalty, complaining of being unfairly penalised while Hamilton accused his rival of being "over the limit". It was a frenetic race but one which perfectly teed up the finale to the season.
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