Melandri, who joins Ducati after three years at Honda, was 12th fastest during his Tuesday Desmosedici debut, and only 13th fastest by the conclusion of the first post-season test on Wednesday evening at Valencia.

The Italian, who is replacing Loris Capirossi, improved his pace by 0.6secs on the second day, but was still left 1.74secs behind Stoner - and was also slower than new d'Antin Ducati riders Toni Elias and Sylvain Guintoli.

"Today we worked a lot on the engine and electronics, to understand how the bike reacts to every kind of change. It's been demanding because the throttle feeling is very different to what I'm used to," confessed Marco. "This afternoon we started working on the chassis, making some important, if not radical, changes.

"During the last half hour of the day I could feel we were improving and that we were starting to go in the right direction for my riding style. It was maybe too late to better my lap time but the sensation was really encouraging. Generally I'm very happy because I'm beginning to understand this bike's huge potential. All I've got to do is work hard to get it set up for my style," he added.