SINGAPORE - Over the past week, the Singapore Grand Prix has been described as an "oven", "intense and draining" and the "hardest race of the year". Or to echo Ferrari's Carlos Sainz dead-on description: "If you survive Singapore, then you're fit for anything else in Formula One."

It is why the Spaniard took his exercise bike into the sauna with him to train earlier in September while Daniel Ricciardo of McLaren wore seven layers of clothing as he worked out. No driver is underestimating the challenge presented by the Marina Bay Street Circuit.

All 20 drivers eventually came through Friday's practice unscathed with Lewis Hamilton going fastest in the first session in 1 min 43.033sec. Championship leader Max Verstappen, celebrating his 25th birthday, was 0.084 seconds adrift in his Red Bull. Ferrari's Carlos Sainz led the way in the second session in 1:42.587.

For Haas' Mick Schumacher, making his debut in the Republic, the hours of video footage studied and simulator sessions clocked paled in comparison to the real thing, said the German.

He did 45 laps in total, with a three-hour break in between. On Sunday, he will hope to finish all 61 laps of the 23-corner circuit, covering 308.706km and probably come close to hitting F1's two-hour maximum threshold limit for a grand prix.

After all, four of the 12 night races - where the cockpit temperatures are about 60 deg C - have gone over 120 minutes. By comparison, the Sept 11 Italian GP was done and dusted in about an hour and 23 minutes.

Sainz, whose best finish here was fourth in 2017, said "To keep mentally sharp is the most difficult because of the heat. You leave me in the car for half-an-hour, driving at a certain speed I could survive but if you want those last three-tenths of performance or focus, it's really mentally challenging to keep them because of how draining it is."

His teammate Charles Leclerc faces an almost impossible task of overhauling Verstappen for the world title. Leclerc is 116 points behind the Dutchman with six races left.

While both Scuderia drivers noted the importance of starting Sunday's race in P1 - eight of the 12 winners here have done so from pole even if Leclerc failed to do so in 2019 - it is not an advantage that Leclerc has converted in 2022.

He won qualifying in Monaco and Baku, both street circuits, but lost to Sergio Perez and Verstappen respectively.

Perez is third in the standings, 125 points behind Verstappen, and has a mathematical chance to catch his teammate. But he dismissed that possibility and said: "It's a matter of time before Max becomes a champion. For me, it's important to try to deliver the maximum possible results for our team and finish our season on a high."

Red Bull will in all likelihood also end Mercedes' record eight year run of constructors' championships and claim their first since 2013.

Lewis Hamilton's own quest for a record eighth world crown will extend to 2023 and while he is winless this season - Hamilton has won at least a race in every campaign since he joined F1 in 2007 - he remains unflustered.

He said: "We've still got six races. I'm still enjoying the challenge and proud of the strength and growth within our team, in terms of the relationships, our focus, just seeing how hard everyone works in a team is, for me, the most inspiring thing."

After Sebastian Vettel's five wins, Hamilton is the next most successful driver here with four victories (2009, 2014, 2017 and 2018). His triumph in 2017 was the first wet night race and came after pole-setter Vettel's car got hit in Turn 1 of the opening lap.

Even the best plans can sometimes get thrown out of the window in seconds. As Red Bull's head of race strategy Will Courtenay noted: "Most of the strategy calls made during the race are dependent on driver pace, tyre degradation and position. Being a strategist is all about managing these factors and trying your best to get the optimal outcome.

"Rain always adds a bit more complexity to the weekend, so you have to be really reactive to the current conditions."

A lot can go wrong after all as the drivers, whose heart rates are around 160-180 beats per minute during the race, navigate 14 left handers and another nine right hander corners while making about 62 gear changes each lap.

McLaren's Lando Norris said: "There's a lot of walls and if you get too close on the inside or outside you can easily make mistakes. Not a lot of room for error, but very enjoyable... When you nail everything and get that feeling inside the car, I love it."

Meanwhile within the paddock, multiple media reports have said Red Bull and Aston Martin exceeded the mandatory US$145 million (S$208 million) budget cap imposed on each team in 2021. There was no official confirmation of any breach with Red Bull boss Christian Horner dismissing the speculation as idle gossip.