Lewis Hamilton and Nico Rosberg look more closely matched than ever before in their time as Mercedes teammates. A title battle that seemed to be drifting towards an inevitable fourth crown for Hamilton has been shaken up since the summer break by a hat-trick of wins for Rosberg, who now leads the championship by eight points.
With the 150 points on offer over the remaining six races of 2016 set to decide who will be champion, ESPN looks at how the two men have fared in the closing stages of the season since being paired together three years ago.
2013
Rosberg: 7th, 8th, 2nd, 3rd, 9th, 5th (Points: 55)
Hamilton: 5th, DNF, 6th, 7th, 4th, 9th (Points: 38)
Hamilton and Rosberg's first season together coincided with a more competitive Mercedes package -- the team claimed eight pole positions in the first 11 races but did not have the race pace to compete regularly with Red Bull. Before the summer break Nico Rosberg claimed two wins (Monaco and Great Britain), before Lewis Hamilton claimed his first win for the team at the Hungarian Grand Prix.
For all the optimism of the first half of the season, the team dropped off in the closing stage of the year. Lewis Hamilton endured a frustrating end to 2013, failing to make the podium during the run-in and banging wheels with Valtteri Bottas at the finale to end his season on a low note. Despite being revitalised at Mercedes and claiming five pole positions, Hamilton had never looked completely happy with the car in 2013 -- admitting after the finale he was glad the season was over and that he had failed to live up to his own expectations.
For Nico Rosberg, the story was different. Though he finished the season as second best of the two Mercedes drivers he had the strongest finish and, crucially, scored back-to-back podiums in India and Abu Dhabi which helped the team beat Ferrari to second in the championship.
2014
Hamilton: 1st, 1st, 1st, 1st, 2nd, 1st (Points: 143)
Rosberg: DNF, 2nd, 2nd, 2nd, 1st, 14th (Points: 79)
A lot changed in a year -- Hamilton and Rosberg were now equipped with the class-leading Mercedes W05 and were engaged in a bitter duel for the world title. Coming into the final six races, the momentum had just changed hands. After their collision in Belgium -- for which Mercedes blamed and punished Rosberg -- Hamilton had forced his teammate into a mistake in Italy, giving him the race win. It was a sign of things to come -- Rosberg looked like a beaten man from the moment Hamilton found his form again.
That Italy win was the first of five in a row for Hamilton, who had been 29 points down on Rosberg after Belgium. That gap soon evaporated when Rosberg encountered race-ending problems in Singapore, before the German crumbled under pressure from Hamilton in the rain at Suzuka a week later. A clumsy lunge for the lead in Russia at Turn 1 ended his chances of victory, before the season-defining moment at Austin -- Hamilton forcing his way past Rosberg's weak defence in Austin to snatch the lead and victory from his title rival.
Rosberg finally returned to the top step in Brazil, leading Hamilton in a Mercedes one-two, leaving him 24 points behind with Abu Dhabi's controversial double-points finale to come. As it turned out, the derided points format would never be an issue -- Hamilton beat Rosberg off the line and into the lead at Turn 1. Rosberg, who needed Hamilton to finish outside the top two to have any chance, then suffered an ERS failure which soon dropped him out of contention and out of the points. Memorably, late in the race Rosberg was advised to retire the car but responded by saying he wanted to take the car to the end, but the day, and the championship, was Hamilton's.
2015
Hamilton: 1st, 1st, 1st, 2nd, 2nd, 2nd (Points: 129)
Rosberg: 2nd, DNF, 2nd, 1st, 1st, 1st (Points: 111)
Coming into the final six races in 2015 Hamilton was in a much more comfortable position, leading by 41 points. Mercedes had just mysteriously dropped off the pace in Singapore but bounced back in style in Japan, with Hamilton leading Rosberg home in a comfortable one-two. Having claimed pole position in Sochi a fired up Rosberg led the early stages of the Russian Grand Prix, only to encounter a throttle problem on lap seven which ended his race and all but ended the championship fight.
Hamilton would claim the win and the title at the U.S. Grand Prix, which saw Rosberg make a mistake while leading late on. Infamously, Rosberg threw his cap back at Hamilton after the race as they waited to take the podium, hinting at lingering problems between the two after another bitter campaign. The bad blood continued in Mexico, with Hamilton taunting Rosberg's claim that "a gust of wind" had led to his costly error in Austin. With the title secured, Hamilton seemed to take his eye of the ball -- in the days before Mexico's return race he was involved in a minor car accident in Monaco -- and Rosberg returned to the top step.
Seemingly revitalised from that victory, Rosberg led Hamilton across the line in Brazil, where the latter grew frustrated at Mercedes' decision not to put him on an alternate strategy. Rosberg then rounded off the season with a dominant victory over Hamilton in Abu Dhabi. Though much was made of Hamilton losing motivation after his title win the three-race streak gave Rosberg renewed confidence he could beat the three-time world champion, and he would go on to win the next four races of 2016.
2016 verdict
Nico Rosberg looks readier than ever to win his first world championship. Though Hamilton's problems gift-wrapped him a win in Belgium before the Brit's slow start in Monza helped Rosberg to another, he looked in commanding form last time out in Singapore. It is also important to note that, for whatever argument there is for Hamilton going off the boil after winning last year's title, Rosberg's strong finish last year carried into 2016 and meant he always had the points in the bank to make this year a genuine fight.
But what the last three years have proven is how dangerous Hamilton can be with a little momentum, while 2014 proved his ability to take wins and a championship from another driver. Six races is ample time to get a run of form going again but he will be fully aware he went eight without a win across the end of 2015 and 2016. However, looking at the tale of the tape, it is hard to look past a fourth world title for Hamilton.
For all his impressive drives this year and at the tail-end of 2015, we are still yet to see Rosberg snatch a win from another driver. The last two seasons are hardly ringing endorsements of his ability to win a title: he crumbled in 2014 and only got a run of form together in 2015 when there was nothing left to play for. His attitude has seemed to swing between one of supreme confidence and lingering self-doubt in 2016. However if Rosberg has learned the lessons of the last two years, with momentum and the points gap crucially on his side this time around, it could finally be the year he joins his father Keke in the pantheon of F1 champions.