Reigning seven time MotoGP world champion Valentino Rossi was delighted after his perfect pre-season form carried over to Qatar on Thursday night.

The Fiat Yamaha rider had been fastest on all four days of previous 2010 testing, at one of his favourite circuits of Sepang in Malaysia, but the Losail night test - traditionally a happy hunting ground for Ducati's Casey Stoner - presented a very different challenge.

Testing began at 6pm under the floodlights at the desert track and Rossi was in command from the word go, finding yet more improvement in the 2010 M1 at a track he hasn't won at since 2006, when it was a day race.

A break for 'dinner' saw both Stoner (Ducati) and star rookie Ben Spies (Yamaha) better Rossi's time, but the Italian was determined to finish the night on top and improved again on his last run to regain first place.

Rossi thus finished the opening night 0.315sec clear of Stoner - winner at Qatar for the last three seasons - with Spies 0.552sec from the top in third and the final rider within one-second of Rossi, after another excellent performance for the Monster Yamaha Tech 3 team.

"I am so happy today because this isn't one of our best tracks and to come here and be fastest shows what a great job Yamaha has done with this new M1," said Rossi. "To start with the track was quite slippery but anyway we were still fast, and as the track started to improve I felt better and better.

"We are quite competitive and this gives me a good feeling, and I was happy to make this quick lap right at the end. We still have to decide the right tyre and the best setting for it, and we will keep working on the electronics but the most important thing is that we're faster than last year!

"Tomorrow we will continue with our work and try to finalise everything before the race."

Underlining the strength of the new Yamaha, all four M1 riders were in the top seven on Friday - with Tech 3's Colin Edwards in fourth and Rossi's team-mate Jorge Lorenzo, making his return from a hand injury, in seventh (+1.436sec).

The top Honda rider was LCR's Randy de Puniet in fifth (+1.186sec), with Repsol Honda's Andrea Dovizioso one place behind the Frenchman. Stoner's team-mate Nicky Hayden was eighth (+1.453sec), with Pramac Ducati rider Mika Kallio ninth (+1.521sec).

Dovizioso's factory RCV team-mate Dani Pedrosa was only tenth (+1.645sec) while Rizla Suzuki will also have hoped for better than eleventh and 17th for Loris Capirossi and Alvaro Bautista.

The final night of 2010 MotoGP pre-season testing starts on Friday evening. The first race of 2010 will then take place back at Qatar on the evening of April 11.