A relaxed Marc Marquez put down an early marker as the reigning MotoGP World Champion led the way the opening day of the Sepang test.

Marquez set a fastest time of 2m 00.286s to take the top spot by half a second from Italy's Valentino Rossi on the Factory Yamaha, with team-mate Dani Pedrosa third quickest (2m 00.906s).

The young Spanish star began the test on the 2013 RC213V before switching to the 2014 model, setting the fastest time on lap 52 of the 62 laps he completed in Malaysia.

Marquez admitted afterwards that he was 'surprised' by his pace as official pre-season testing got underway.

"We didn't try many things today, we ride with the same bike that we finished with in Valencia at the final test," he said.

"Tomorrow we will start to test some things but at the moment I feel quite good and the track was quite good.

"At this point last year I felt more nervous but this year I am more relaxed. On the race weekend I will feel more pressure, but anyway normally I work well under pressure.

"Today already the lap time was quite fast. It was a great surprise but I think in Malaysia it depends a lot on the conditions on the track. We can see that many riders were fast and I think tomorrow and on the third day they will improve a lot."

Marquez has identified braking stability and smoother power delivery on corner exit as two areas where he hopes the Honda will improve this season.

"We are trying to improve a little bit the braking stability. It is important also to have a smoother engine for the exit of the corner and improve rear grip," he said.

"Sometimes one thing does not make a big difference but if you put them altogether it will be better.

"I'm happy with how this first day went and to have achieved my goal of regaining my feeling on the bike.

"Even if you do five hours a day in the gym, when you are here you are completely destroyed because everything is different on the bike and you are stiff. Now I feel tired but tomorrow will be better."