Colin Edwards made a charging start to his penultimate MotoGP event as a Yamaha rider, leading the factory's challenge with sixth place for the Monster Tech 3 team during Friday practice at Sepang in Malaysia.

Extensive work on the set-up of his YZR-M1 during the two winter tests in February paid instant dividends for the Texan, who was able to find a fast and consistent rhythm.

Edwards, who will ride a Suter-BMW for the Forward Racing team next season, lapped in fourth place for the majority of the afternoon session, which he finished as the best non-Honda rider.

The 37-year-old was 1.7sec behind pace setter Dani Pedrosa, but only 0.3sec from third place Andrea Dovizioso.

"Today was a really good day and I was fast straight out of the crate," said Edwards. "I was fourth for almost the whole of the second session and I'm happy to end up sixth. We pretty much ran the bike with the same set-up that we left the second test with in February and it felt great.

"That proves that testing twice here and riding lots of laps in punishing heat does work because we tried a couple of small changes on the bike but pretty much came back to the test setting.

"The first thing you need here is front-end confidence and the front was awesome right from the start. That gave us an opportunity to focus on improving rear grip and that's critical here. If you can get a set-up where the rear tyre is driving and not spinning, you can have a good race. The track is lacking a bit of rubber on it compared to the test but apart from that it feels pretty good.

"The conditions are typically hot here in Sepang but maybe it doesn't bother me as much as some of the others. I'm from Texas so I live in this type of heat and humidity and I'm pretty much used to it.

"Even though I've done millions of laps around this track I've never finished higher than eighth, but after a start like today I'm confident that I can do much better than that."

With the Factory Yamaha team lacking 2010 world champion Jorge Lorenzo, and team-mate Ben Spies struggling with rib injuries, Edwards looks set to carry the M1 challenge this weekend.

Rookie team-mate Cal Crutchlow's third visit of the year to the fast and technical Sepang circuit didn't run as smoothly as he had hoped. The Englishman worked hard to find greater grip and turning on corner entry, but could only manage 15th place.

"Today was pretty tough to be honest and not just because of the extreme heat and humidity," confirmed Crutchlow. "We're searching for front and rear grip and when the conditions are as hot as here, that's not an easy task. I'm missing side grip on the rear and like a few other tracks we've been to recently, I'm having problems getting the bike turned.

"The track is obviously in a lot different condition to when we tested here because the times are about two-seconds slower, but I'd hoped to be a bit higher up the rankings.

"I knew it was going to be a tough day because I found this place hard during the two tests at the start of the year. It is such a long lap that it is difficult to get a lap nailed perfectly, but looking at the timesheets I am a second off fourth place and I'm not happy with the bike, so that gives me some encouragement.

"We'll continue working hard as always tomorrow and I'm sure we can find a few tenths to move up the order."