Lewis Hamilton finished Friday on top of the times at Sepang, but it was a far from easy day for the Mercedes driver.
Hamilton stopped on track in FP1 with what turned out to be an inlet issue, and by the time it was addressed he had missed the first half of FP2.
He also suffered with telemetry issues in both sessions, which further restricted his lappery.
"Firstly it was just an amazing job done by my guys to rebuild the car and get the engine back on, and gearbox and everything, and get me back out," said Hamilton.
"I'm very grateful for that. Particularly here where it's so hot it's so difficult for the tyres and everything, it was really important to get back out and do some laps."
He added that the lost track time was costly: "It affects you quite a bit. Fortunately I got a few laps of a longer run at the end, but in terms of my set-up I've not made any changes, so I've just driven what I have.
"It's quite a bit off with where I probably need it.
"I know my lap wasn't spectacular. As I said I think I've got some improvements I can make with the balance and the settings, they were all kind of brought from the last race. I'm sure we'll tweak it and improve it a little bit."
Hamilton also said he was impressed by the main competition.
"The Ferraris look great, they really do. It's surprising to see how good their times are. We'll see whether that continues through the weekend."