SINGAPORE — Lewis Hamilton aims to turn up the heat in his bid for a sixth Formula One championship at this weekend's Singapore Grand Prix. 

The Mercedes driver heads into Sunday's race with a 63-point lead over teammate Valtteri Bottas. 

As with last year's race, drivers can expect sweltering heat and humidity.  In addition to the heat, a thick haze has set in over the city-state with advisories issued from the national government over "unhealthy" air conditions. 

Hamilton will be hoping for a repeat of the 2018 race here when he won comfortably from pole position to extend his championship lead. 

He was on a major roll entering last year's GP, having won four of the past five races.  While he already has eight wins this season, the British driver last won at the Hungarian GP in early August. 

"The offset schedule and the climate make it a demanding weekend for the team," Mercedes team principal Toto Wolff said of the night race. " Temperatures in the garage can easily reach 40 degrees Celsius (104 F) or more with high humidity levels as well.  It's a tough environment to work in and it's equally challenging for the drivers and the car itself." 

Hamilton has won here the last two years.  A win on Sunday would move him a step closer to his third straight championship and sixth overall, moving him just one away from equaling Michael Schumacher's all-time record of seven titles. 

Ferrari driver Charles Leclerc heads into Singapore having won the previous two races this season.  After his first-ever F1 victory in Spa at the Belgian GP, the 21-year-old Leclerc became the first Ferrari driver to win the Italian GP since Fernando Alonso in 2010. 

Leclerc, who is now fourth in the standings, finished ninth for Sauber here last year. 

"Singapore is maybe the toughest track for us drivers physically, just because of the heat and the humidity," Leclerc said. " After two positive weekends in Belgium and Italy, the race in Singapore doesn't look as good on paper for us, because of the very different circuit layout, featuring lots of slow corners and fewer straights ... but we will give our all to have a good result." 

The 5-kilometer (3.1-mile) Marina Bay Street circuit is one of the hardest tracks for overtaking in F1, so whoever takes pole on Saturday will have the upper hand.  The driver leading the field has won eight times in the past 10 years. 

Max Verstappen, third in the drivers' standings, has been on the front row at Marina Bay the past two years while Bottas has never started in the top three. 

Ferrari's Sebastian Vettel and Hamilton are the only two drivers on the grid with victories at Singapore — with four wins each. 

But Vettel, whose contract ends in 2020, is now 22 races without a win.  He has dropped down to fifth in the championship, 115 points behind Hamilton. 

"We have seen before that anything can happen in this race, so the final result is hard to predict," Vettel said. " Off the track, there will also be a lot of pressure on the teams as this race is back to back with Russia." 

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