Jorge Lorenzo began what looks like being his title-winning weekend, at Sepang in Malaysia, with a close third place in Friday practice.
With title rival Dani Pedrosa injured, Lorenzo needs to score just seven points on Sunday to decide the title three rounds early.
The Fiat Yamaha rider finished just 0.174sec behind team-mate Valentino Rossi in practice, with the Repsol Honda of Andrea Dovizioso between the two M1 riders.
"Today conditions were quite difficult, with the high temperatures and a dirty track. I'm happy though because I felt good on the bike, I rode fast and I was close to the first position," said the Spaniard.
"We rode with the old engine again today but maybe we will try the new one tomorrow.
"We need to work on the fourth sector, which is where we're losing time at the moment, so tomorrow we will concentrate on that and try to improve further."
Lorenzo rode from last to fourth in last year's wet Sepang race.