The new track surface at Sepang was a key talking point for drivers ahead of the Malaysian Grand Prix, where Jenson Button will reach a major landmark.
Resurfacing and reprofiling work has been carried out on the circuit, as well as run-off, kerbing and drainage changes.
One notable amendment has been made to the final hairpin, which now features a significantly raised inside corner.
"It's dark, so that's a major difference," joked McLaren driver Button, who will compete in his 300th grand prix.
"If it's clear then the temperatures are going to be very high on the track, which obviously has quite a big effect on the way that the tyres work.
"It's very smooth, from what I see, and the last corner is very different with the off-camber.
"I don't know if it's similar to Sochi or not, but it seems like it is, with the bitumen and the way the asphalt is, so it might be a completely different circuit [as a result].
"But we won't know until [free practice] tomorrow."
Formula One championship leader Nico Rosberg, who holds an eight-point advantage over Mercedes team-mate Lewis Hamilton, added: "It will be a big challenge because it will be very different and we all need to adapt to the new asphalt.
"We don't know how it's going to handle here."
Button first raced in F1 for Williams 16 years ago and has 15 race wins to his name, having claimed the world title in 2009 while with Brawn GP.
The 36-year-old described his surprise at preparing for his 300th race - a feat also achieved by his former Brawn team-mate Rubens Barrichello.
He said: "I remember when Rubens got to 300 and it was unbelievable that he got to 300. I thought 'I'm never going to race that long'.
"When I started in 2000 I remember speaking to my dad and he was saying 'how long do you think you're going to race for, will you still be racing in your thirties?' and I was like 'no, I'll be done by the time I'm 30 years old!' And here I am at 36 and this weekend at the start of my 300th grand prix."
Button's team-mate Fernando Alonso has been hit with a 30-place grid penalty as he tests an upgraded Honda engine.