Valentino Rossi already 'stronger' than in MotoGP 2013

After a disappointing 2013 campaign with Yamaha, when he was outclassed by team-mate Jorge Lorenzo, Rossi said the first six races of 2014 would determine whether he retires at the end of the year.

He began preparations for that six-race trial in style, outpacing Lorenzo on all three days at Sepang and ending with the second fastest time overall, less than two tenths down on last year's champion Marc Marquez.

Rossi said that lap time, allied to genuine improvements on the bike, were a cause for optimism.

"I'm very happy about the test, because I improve a lot compared to last year," he said.

"I improved especially in braking, [where] last year I suffered very much, so it is a positive test.

"Especially [on day three] I was very fast, and that lap was first time in my 20-year career under 2m00s at Sepang, so I'm proud of this.

"It is true Marquez is faster not just today but all three, but anyway I feel competitive and I feel stronger than last year."

Rossi warned though that Yamaha still needs to improve in every area if it is to take the fight to Marquez, who topped the timesheets on all three days and was the first rider to complete a full race simulation on this year's reduced 20-litre allowance of fuel.

"The start was good. Now we have to work and improve," Rossi said.

"We have a lot of areas we have to improve, [but] we still have a lot of stuff to try that we keep for the next test.

"Marquez is impressive, especially with the [race] simulation, but it is also true he did [his fastest time] it in the morning when the track is faster, so I think the difference is a bit less.

"But if we want to fight with him we have to improve everywhere."