Lewis Hamilton won a crazy, twice-halted Saudi Arabian Grand Prix for Mercedes on Sunday to go level on points with Red Bull rival Max Verstappen and set up a winner-takes-all title showdown in Abu Dhabi.
Here are the championship permutations as we buildup to arguably the most exciting climax in F1 history.
What happened in Saudi Arabia?
On a chaotic night in Jeddah, the first race in the Gulf kingdom took almost as many twists and turns as an already astonishing and enthralling rollercoaster season - and also left a bitter aftertaste.
There were crashes and collisions, safety cars, red flags, and claims of dirty driving after seven-time world champion Hamilton hit the back of Verstappen's suddenly slowing car on the super-fast Jeddah Corniche Circuit.
Extraordinary, at times angry, radio exchanges between the race director Michael Masi and the top two teams filled the airwaves.
Hamilton would end up taking the chequered flag with Verstappen second. Hamilton's Mercedes teammate Valtteri Bottas completed the podium after speeding past Alpine driver Esteban Ocon on the home straight.
So who leads the championship?
With a bonus point for the fastest lap, Hamilton moved alongside Verstappen at the top of the standings with 369.5 points after 21 races.
Mercedes extended their lead in the constructors' championship to 28 points and a record eighth successive title looks likely.
When is the final race?
The end of a thrilling season climaxes at the Etihad Airways Abu Dhabi Grand Prix at Yas Marina Circuit on Sunday, December 12.
What do Hamilton and Verstappen need to do to be crowned champion?
There are a maximum 26 points up for grabs in Abu Dhabi - 25 for a race victory and one for the fastest lap around the remodelled Yas Marina track.
The simple equation is that whoever finishes higher will win the title.
Verstappen leads Hamilton 9-8 on wins for the season, however - meaning that the 24-year-old Dutchman will be champion if neither he nor Hamilton scores another point in Abu Dhabi.
Hamilton is chasing an unprecedented eighth title while Verstappen will be hoping to win his first championship.
Hamilton beats Verstappen in Saudi Arabian GP to set up nail-biting finish to F1 2021 in Abu Dhabi
What can still be decided?
Mercedes top the constructors' standings on 587.5 points ahead of Red Bull on 559.5 points, a 28-point differential.
With 25 constructors' points awarded to the winning team, Mercedes will be crowned champions for an eighth consecutive year if either Hamilton or Bottas win the race, regardless of how high Red Bull finish.
Red Bull could conceivably usurp Mercedes if both their drivers - Verstappen and Sergio Perez - finish first and eighth or higher and neither Mercedes car finishes in the top 10.
Haas will be aiming to finish the season with at least one point as they are the only team currently on zero.
