As the 2015 Formula One season edges ever closer to its conclusion, most of the field will head to the Brazilian Grand Prix feeling they have some kind of point to prove.
Nico Rosberg will want to show the world he can be a genuine championship contender next season, while Sebastian Vettel will be desperate to make amends for a dreadful outing in Mexico City.
Kimi Raikkonen, Nico Hulkenberg and Carlos Sainz Jr. need big performances to close the points gaps to their higher-scoring, better-performing team-mates. Daniel Ricciardo will leave no stone unturned in his bid to regain his position as the top Red Bull driver, but Daniil Kvyat will do everything in his power to protect his four-point cushion.
Valtteri Bottas wants to remain fourth in the championship, while Felipe Massa is aiming to catch him. The McLaren super team of Fernando Alonso and Jenson Button have the two Saubers in their sights and Pastor Maldonado needs to show he's capable of leading Lotus in 2016.
But the driver with, arguably, the least to prove is the man to watch as we head into the Interlagos weekend.
Lewis Hamilton, three-time world champion, 10-time 2015 race winner and the polesitter at 11 rounds so far, had his party mood severely soured just a week after clinching the title.
No longer constrained by the need to score points and having shown no reluctance to go wheel-to-wheel, he'll be out to set the record straight in Brazil—and if Rosberg once again brings his A-game, we could be in for a very special race.
Hamilton cut a disconsolate figure on the podium at the Autodromo Hermanos Rodriguez. One step up and to his left, team-mate Nico Rosberg was celebrating winning his fourth race of the season in commanding fashion.
A fourth consecutive pole position was followed by a race in which he was never truly challenged, and his lap of 1:20.521—the fastest of the race, two-tenths quicker than Hamilton's best—secured the first hat-trick of his F1 career.
The German needed to hit back after his error in Austin gifted Hamilton the win, and he couldn't have asked for a better result. The angry, frustrated, cap-throwing loser from the Circuit of the Americas had become a smiling, waving winner in the space of just one week.
Hamilton—the smiling, waving winner of the United States Grand Prix—had gone in the opposite direction.
No driver likes to lose, but Hamilton seemed to take this defeat unusually hard—in part, no doubt, because he felt he had a golden opportunity to win. Mercedes had initially planned a one-stop strategy for both drivers but opted to switch mid-race to a two-stop.
Rosberg later revealed he hadn't particularly wanted to make his own second stop, but—at least as far as we can tell from the team radio messages broadcast on the live TV coverage—he didn't argue with the decision and came in as requested on Lap 46.
Hamilton was less compliant. Sensing an opportunity to make one fewer stop than his team-mate and have at least a chance of winning the race, he questioned the call and told race engineer Peter Bonnington that his tyres were still good.
The exchange between the pair went on for more than a lap, eventually culminating in Bonnington stating it was an "instruction." Hamilton made a point of telling Mercedes (and the listening world) he disagreed with the call, pitted, and—with the circuit layout making an on-track pass between identical cars almost impossible—gave up any realistic chance of a victory.
His post-race comments to the press, reported by BBC Sport, indicated he felt hard done by. Asked if he thought the team had acted to ensure Rosberg won, Hamilton said, "I never think those kind of things. But I know the team has felt the need to be extra warm [to Rosberg]."
Asked what he meant, he replied, "I do know what I mean but I'm not going to say what I mean. You should ask Toto Wolff and Niki Lauda. You should put those questions to them about how they feel about it, and what they have to do behind the scenes to keep him happy."
Hamilton also had a small dig at Rosberg in the post-race press conference. While congratulating his team-mate on the win, he referred back to the "gust of wind" that Rosberg blamed for costing him the U.S. Grand Prix win.
Despite having the title in the bag and having proved beyond any doubt that he is the top dog at Mercedes, Hamilton looked rattled and sounded a little bit paranoid. With respect to Rosberg—who is a very good racing driver—the new world champion appeared to have temporarily taken over the German's role as the downtrodden, aggrieved No. 2.
Hamilton seemed to have recovered soon after the race. He attended the Americas premiere of new Bond film Spectre, played with a jaguar at a big cat rescue centre and received the GQ Mexico International Sportsman Of The Year award at a ceremony in Mexico City.
He then headed to New York to attend a charity night before flying over London to throw a 60th birthday party for his mother, keeping his fans updated all the way on Instagram and Twitter. Hamilton looked like he was back to his normal self, the defeat to Rosberg nothing but a distant memory.
But when he arrives in Sao Paulo, the 30-year-old will switch back to business mode, Mexico will be fresh in his mind—and no driver on the grid will have a greater desire to beat his team-mate in Sunday's race.
Interlagos has been both cruel and kind to Hamilton. In 2007, he missed out on the world title by a single point when he finished seventh, but he won it by the same margin the following year after perhaps the most thrilling final lap an F1 season has ever seen.
In the six Brazilian grands prix since that memorable afternoon, Hamilton has only stood on the podium twice. He's either spun or had contact with another car in four of those races and retired from one of the others with a gearbox problem.
It's the only circuit on the current calendar at which he has raced more than twice but never won—and as a huge fan of Sao Paulo's own Ayrton Senna, he desperately wants to break his duck.
From a neutral perspective, the fight between the Mercedes drivers has been a little too one-sided in 2015; in the early and middle part of the year, Rosberg simply had no answer to Hamilton.
But from Suzuka onward, there hasn't been a lot between them.
Rosberg, 30, has been on pole four times in a row, and the Silver Arrows have had broadly similar race pace. The difference has been Hamilton's killer instinct and superior race craft, a reliability issue in Russia and, of course, that Texan gust of wind.
There's no doubt Rosberg desperately wants to round out the season with a hat-trick of wins to seize the momentum going into 2016, but Hamilton's words after the Mexican race indicated he felt wronged—this is where he wants to put things right.
And if that's not enough of an incentive, he also has the target of a first victory at Interlagos—home track of his idol Senna—to think about.
Hamilton has the ability to win, the car to win and more than enough motivation to blow Rosberg out of the water. The 2015 season tells us that's more than likely what he will do.
But what if he doesn't? How will Hamilton react if Rosberg beats him again in another straight fight?
Whichever Mercedes driver comes out on top in Brazil, Hamilton will surely be the one to watch—before, during and after the race.