Andrea Dovizioso, who took pole and a podium last weekend in Japan, carried that momentum over to Friday practice for the Malaysian MotoGP.
The only Repsol Honda rider present at Sepang briefly deposed fellow Italian Valentino Rossi on his was to a close second position, just 0.109sec behind the Fiat Yamaha rider.
Dovizioso took his first ever MotoGP podium at Sepang in 2008 and is now battling Rossi for fourth in the 2010 championship.
“I'm happy with this first session at Sepang because we were fast from the very beginning of the practice period," said Dovizioso.
"Today the conditions were really extreme in terms of the heat - even more than we're accustomed to here - so physically it was very hard. We started from a good base today however.
"We will continue work on set-up improvements and adjustments to the electronics to increase the stability at the front end under braking.
"But I think we have found the limit of the tyres in these conditions, so I will also try to adapt my riding style to make further improvements to the lap time tomorrow. Overall we made a good start today.”
Dovizioso's team-mate, Dani Pedrosa, is not taking part in the Malaysian Grand Prix as he recovers at home in Spain from the broken collarbone he sustained in Japan one week ago.
Dovizioso was one of two riders that crashed out of last year's wet race.