Both Formula One world championships have already been wrapped up but there is still plenty to play for in the final two rounds of 2017. ESPN picks out five talking points ahead of Brazil and Abu Dhabi.
The battle for second place
Two months ago, nobody would have considered Sebastian Vettel to be scrapping over the runner-up spot in the championship. But a disastrous run of results -- including two retirements -- across the three Asian races in Singapore, Malaysia, and Japan left the Ferrari driver with a mountain to climb in the championship. Having ultimately lost out on the drivers' title to Lewis Hamilton in Mexico, the German is faced with the prospect of being overtaken in the standings by another Silver Arrow.
Valtteri Bottas is 15 points behind Vettel, a deficit that is far from inconceivable to overturn, especially when considering that Mercedes has had a car at its disposal capable of winning five of the last seven races. The problem for Bottas is that he has been well off the pace of both teammate Hamilton and Vettel since the summer break. The Finn managed his first podium in four races in Mexico, but will need to recapture the form that saw him claim two race victories in the first half of the season if he is to complete a Mercedes stranglehold at the top of the championship.
Can Red Bull end the season on top?
Red Bull's true competitiveness has been masked by a plethora of engine-related reliability problems this season, but in the last four races we have seen a glimpse of the RB13's outright pace. Daniel Ricciardo may have struck lucky with his victory in Baku during a crazy race, but the Milton Keynes-based squad is hitting some serious form at the end of the campaign. Max Verstappen's mid-season reliability curse seems to have shifted onto Ricciardo's car, allowing the Dutchman to challenge in Singapore -- until he was caught up in a Ferrari sandwich -- before taking dominant wins in Malaysia and Mexico. Across the past four races Verstappen has been F1's top-scorer, bagging a total of 80 points, 10 more than the newly-crowned champion.
Most impressive was the team's performance in Japan, where Verstappen ran Hamilton close for victory, and Austin, where Verstappen recovered from towards the back of the grid to finish third on the road, only to lose his podium spot in controversial circumstances. Both of these circuits were not expected to favour the characteristics of Red Bull's 2017 challenger, which will leave the team full of confidence heading to Brazil's Interlagos circuit -- a track that requires good aero efficiency -- and Abu Dhabi, particularly the Yas Marina Circuit's twisty final sector.
A tight midfield fight
Arguably, the most fascinating battle still to be resolved is the one for sixth place in the constructors' championship. Just six points separates Toro Rosso, Renault and Haas in eighth. Red Bull's sister squad has managed just a single point in the last four races, having been disrupted by a series of changes to its driver line-up. Based on current form, the Faenza-based outfit is set to lose millions in revenue if it slips to seventh or eighth in the standings, though a large windfall from its 2018 engine deal with Honda would soften any financial blow.
Renault looks best-placed to capitalise. Boosted by new recruit (and former Toro Rosso driver) Carlos Sainz, who replaced the low-scoring Jolyon Palmer in Austin, the French manufacturer has the pace and driver ability to score points with both of its cars in the final two races. Much will depend on whether Renault can solve its reliability issues, which has stunted the team's progress in recent races. One solid points haul could be enough for either Toro Rosso, Renault or Haas to seal sixth, while a big result might even elevate one of those teams above fifth-placed Williams, sitting just over 20 points further up the road.
Will Honda's progress continue?
2017 has been another season to forget for McLaren and Honda, having been marred by poor reliability, a lack of engine performance, and a divorce. It took until the eighth race of the year before McLaren finally scored points, which have been few and far between. With reliability still thwarting the team, McLaren will be relieved to finally be seeing the back of Honda after the chequered flag falls in Abu Dhabi, following another torrid campaign.
A flurry of grid penalties for surpassing the allowed quota of engine elements have held Fernando Alonso and Stoffel Vandoorne back in recent races. But there have been promising signs. Alonso said McLaren had the best car of the entire field during qualifying in Mexico, after ending Q1 just 0.192s slower than Hamilton's leading lap time -- emphasising the strengths of McLaren's chassis, as well as improvements made on the engine side. Alonso was able to fend off attacks from Vettel and Hamilton along the 1.2km main straight at the Autodromo Hermanos Rodriquez, giving Honda some encouragement heading into its new venture with Toro Rosso in 2018.
F1 futures at stake
While most of the driver dominoes have fallen into place for 2018, a few seats remain up for grabs. Toro Rosso is yet to confirm its line-up for 2018, but is expected to run Pierre Gasly next year following his debut in Malaysia. It is looking increasingly likely that he will be joined by two-time WEC champion and recent F1 debutant Brendon Hartley. Both men will be looking to end the season strongly to cement their places in the team, following Daniil Kvyat's demotion from the Red Bull driver programme.
Kvyat may yet have an F1 lifeline in the shape of Williams, with the team yet to announce who will partner rookie Lance Stroll next year. Robert Kubica and Paul di Resta are also vying for the seat, following recent private tests. Sauber's situation is also unclear, particularly regarding the future of Pascal Wehrlein -- an outside contender for the spare Williams seat -- with Ferrari keen to place at least one of its young drivers in its customer team. Marcus Ericsson may have a stronger likelihood of retaining his seat, given his rumoured ties with Sauber's owners. Despite failing to score in 2017, he has recently out-performed Wehrlein in qualifying.
Following Felipe Massa's announcement that he will be retiring from F1 (for the second time) at the end of this season, expect more emotional scenes at his home race in Brazil this weekend. Massa will be looking to regain 10th place in the drivers' standings from teammate Lance Stroll in his final two grands prix, before he bows out of F1 for what will surely be the final time.