From former bunk-mates to fierce F1 rivals
Mercedes cautious as Rosberg and Hamilton prepare for a tough GP in downtown Singapore
They were buddies and bunked together for two years as teammates in the European karting championships 14 years ago.
They remained friends after graduating to Formula 1 in 2006 and 2007, respectively.
Over the last couple of years, though, the relationship between Nico Rosberg and Lewis Hamilton has become frayed amid the tussle for the drivers' championship.
If they remain pals, it has been put firmly on the backburner, as motor racing's biggest show gets set for this weekend's 2016 Formula 1 Singapore Airlines Singapore Grand Prix.
The Mercedes racers have dominated the season so far, winning 13 of the 14 Grands Prix, with Red Bull's Max Verstappen the only other driver to claim victory when he took the chequered flag in Spain.
With seven races to go, including Sunday's night contest along the streets of downtown Singapore, and only two points separating leader Hamilton and Rosberg, there is much at stake for the two drivers, who have turned the campaign into a two-way scrap.
But, like all street tracks, the 5.065km Marina Bay circuit is tricky, with overtaking notoriously difficult.
In the heat and humidity, it is possibly the most torturous race for the drivers, with the bumpy terrain merciless in sapping the energy of the pilots.
It is why Mercedes team boss Toto Wolfe was guarded about their chances.
"As we have seen before, it's a race where a single problem can cascade into many more as the weekend progresses," Wolfe said, in a Mercedes press release after touching down in Singapore.
"We have to optimise everything to get a solid result. We didn't manage it last year and, although we believe we now understand why, only performance on the racetrack can prove our conclusions right."
The mighty German outfit was in a similarly dominant position this time last year, but failed to appear on the podium here, after Hamilton retired midway because of a faulty power unit, while Rosberg only managed fourth spot.
The race ended with Ferrari's Sebastian Vettel and Kimi Raikkonen finishing first and third, and Red Bull's Daniel Ricciardo second.
Mercedes did win in 2014 when Hamilton won for the second time at Marina Bay, but Rosberg had to retire with an electrical problem.
HEAT IS ON
There is huge pressure on Rosberg.
The German is still chasing his maiden title and his mental strength has come under scrutiny after blowing what was at one stage a 43-point gap over his arch-rival.
The 31-year-old has returned to form after winning the last two races in Belgium and Italy and a triumphant result under trying conditions here on Sunday will set him up nicely for a final flourish.
PHOTOS: REUTERS, AFP
"Singapore is a race that's been up and down for me," said Rosberg.
"I got my second ever podium way back in 2008, but haven't been up there again since, so the target is to change that on Sunday. Of course, it won't be easy. This is a Red Bull track and we weren't so strong here last year."
Hamilton has been his long-time nemesis.
In their karting days, the Briton edged the German to the 2000 Formula A European title.
In the higher category Formula Super A the following year, Rosberg finished 16th, again a place behind his teammate.
Hamilton had the upper hand after arriving at Mercedes in 2013, especially in the last two seasons when Rosberg played bridesmaid to his successive championship wins.
Despite the challenge of racing at Marina Bay, Hamilton, 31, is brimming with confidence.
"When you look at how far we've come as a team this season, from the position we were in, then I realise I'm in a phenomenal position," said the Briton, in the Mercedes press release.
"We're still leading both world championships and there are still so many great things to achieve together, even before this season is through.
"Singapore is a challenge with the heat and humidity, but it's a street circuit, which I love."
While he has never won in Singapore, Rosberg has been a steady hand in the tight street circuit and has pulled off some exceptional overtaking manoeuvres over the years.
If he has any advantage over his Mercedes teammate, then it will be Hamilton's win at all costs mentality.
It is exciting and stirs up much fuss in the stands, but it also leads to mistakes, like in 2010 when he collided with Red Bull's Mark Webber and was forced to retire.
But Hamilton has won twice in Singapore, the first with McLaren in 2009, and his racing style has led to three titles.
Nevertheless, Rosberg is optimistic.
"I approach each weekend aiming to win the race. The points gap has gone up and down but I've taken it one race at a time," he said.
"That's the best way for me, as you can see by how the gap is now."
Queen will raise bedlam at the Padang 24 hours before the main action gets underway, fitting perhaps, because a pair of Mercedes drivers could rock and roll on Sunday along Marina Bay.
Ferrari and Red Bull will be on it I'm sure, so we've got a big fight on our hands if we are up at the front. I love a battle, so I'm excited to see how it plays out.
— Drivers' championship leader Lewis Hamilton
Singapore is a cool city and a great place for Formula 1. the track looks spectacular under the lights and it's always buzzing in town around the race weekend, so I'm really looking forward to getting out there.
— Nico Rosberg, just two points behind Hamilton in the drivers' standings
By the numbers
There will be about 1,600 lighting projectors strategically positioned around the Marina Bay street circuit track. They ensure the drivers can focus on what they do best, racing wheel-to-wheel, with minimal glare and reflections from a wet surface or spray from other cars.