Victory in Japan last weekend saw Repsol Honda rider Pedrosa cut his deficit to Yamaha rival Lorenzo to 28 points with just three races left to run.
Lorenzo will win the title if he finishes third at each race, regardless of what Pedrosa does.
But his rival continues to exert pressure after posting a time of two minutes 1.621 seconds during the morning session - with the afternoon session being blighted by rain, rendering the times meaningless.
The Honda rider's hopes were boosted by the performance of team-mate Casey Stoner. The Australian returned from ankle injuries last weekend and looked closer to the ultimate pace on Friday as he set the second-fastest time, just over a tenth of a second down on Pedrosa.
That left Lorenzo third on the first of the factory Yamahas, with the satellite Tech 3 machines of Andrea Dovizioso and Britain's Cal Crutchlow fourth and fifth.
Ben Spies was next up on the second factory Yamaha, ahead of Stefan Bradl and Nicky Hayden, who was the quickest of the Ducatis.
Alvaro Bautista was ninth for Gresini Honda as the team return to the circuit where their rider Marco Simoncelli was killed in a horrific crash last year.
Valentino Rossi, the 2010 winner here, could only manage 11th quickest as his spell with Ducati meanders to its conclusion.
Crutchlow was disappointed to miss out on valuable set-up time during the afternoon, but remains hopeful of a strong weekend.
He said: "It was a shame the rain meant I didn't get to go out on track for the second session because I had some work to do to improve the bike.
"I felt confident right from the start this morning and even though I wasn't pushing that hard because the track was quite greasy, the lap time still came quite easy. Hopefully tomorrow [Saturday] we will have better luck with the weather and we can focus on improving the bike for the race."