Casey Stoner, second and first since returning to MotoGP action after a three-round break to treat fatigue problems, remains on target for a third podium in a row after a close second place in Friday practice at Sepang.

The Ducati star led much of the second half of the session, before losing out to Yamaha's Jorge Lorenzo by just 0.064sec.

The Australian was happy with his pace and physical condition, but admitted he was uncomfortable on the bike.

"The lap times are surprisingly good considering the track conditions, which are definitely suffering from the heat and feel much less grippy than usual here," said the 2007 world champion.

"I'm happy with our pace and with my physical condition; even though it was hard work out there and I was tired by the end of the session, I don't think I was any worse off than anybody else and it is a different world compared to the way I felt at hot races earlier in the year.

"Having said that I didn't feel at all comfortable with the setting on either bike," he declared. "Every time I went out there was a small problem holding us back - at first it was with the front chattering and folding, then we lost grip on the rear.

"There was no use staying out there on a bike that needed to be set up better so I had to keep coming in, which disrupted our rhythm and didn't give me chance to establish any kind of feeling.

"We made progress step by step but we need a better base to start off with tomorrow in order to prepare properly for the race," Stoner concluded.

Team-mate Nicky Hayden set the eighth fastest lap time, 0.067sec behind Toni Elias and 1.2sec from Lorenzo.

"I know my position isn't great but this is still the best Friday I've had in a while and we're only just over a second off the front, which isn't that much around this circuit, so I'm pleased," said the American, who previously rode the Ducati at Sepang in pre-season testing.

"We made a change to the electronics today, which has improved my feeling for the bike, and I was able to lap consistently inside the top ten throughout the session, whereas usually I'm much further off in the first session."

But one thing that still mystifies Hayden is why he continues to be so much slower than Stoner on top speed.

Stoner set the second fastest top speed of 308 km/h in practice (compared with 309.5km/h for Lorenzo) while Hayden only managed 300.3km/h, a significant handicap on a circuit with two long straights.

"Obviously there are a lot of areas we need to improve, like every Friday, but in particular we need to look at why I am fourth from bottom on the top speed charts," he said. "That's strange because we know we have a strong bike so we'll try and fix that tonight because I'd certainly rather be fourth from the top!

"In general it's a good start and I'm eager to see how much we can improve on track tomorrow."