MotoGP world champion Casey Stoner took an early version of next year's Ducati Desmosedici GP9 - which features a carbon fibre frame - to the top of the Monday test times at Catalunya.

Stoner wasn't expected to test the machine until Tuesday, but the threat of poor weather saw the reigning MotoGP world champion - third in Sunday's race - ride the GP9 alongside test riders Vittoriano Guareschi and Nicola Canepa.

Stoner quickly felt at home on the new machine, setting a best time of 1min 42.632secs on race tyres - 0.2secs under his best lap time in Sunday's grand prix - and also set the best lap time of the day, a 1min 41.533secs, with qualifying tyres. Stoner's pole time with the GP8 was a 1min 41.186secs.

"I'm happy with the way today has gone. The objective was to understand whether this new chassis concept has potential and I'd say that for now it looks to be the case," he said of the carbon fibre frame.

"We were quickly into some decent times using the same set-up as the GP8. We barely changed anything to adapt it to the characteristics of the GP9 and I immediately felt an improvement so that is positive. I'm sure that with more time to work on it we can go much faster, although that is not the current brief.

"We'll have time to test it in the winter. Tomorrow we'll get back on my GP8 because we have some important tyre testing to do. There is still a lot of the 2008 season left and we want to be competitive," he declared.

Ducati Corse general manager Filippo Preziosi explained why next year's machine was being given to the factory riders at such an early stage in the 2008 season - Sunday's Catalan Grand Prix having marked round seven of 18.

"We took the decision to allow the factory riders to test the GP9 because it would have been more difficult at a later stage of development and eventually we'd have had to go backwards in certain areas," explained Ducati Corse general manager Filippo Preziosi. "There are some things that are possible to analyse with data such as in the engine or the cycle part but other areas where it is absolutely essential to have the riders' opinions. So it was important to get their feedback to understand if the choices we've made have been the right ones and to get their suggestions."

Preziosi downplayed the significance of the carbon fibre frame, even though it marks a clear change from existing technology. All of Ducati's previous MotoGP machines have had a steel frame, whilst rivals Honda, Yamaha, Kawasaki and Suzuki currently use aluminium.

Carbon fibre is light, strong and extremely stiff - but also has different mechanical properties in different directions, depending on how the fibres are laid, opening up a range of new possibilities.

"Some changes we've made to the cycle part could seem more revolutionary than others but in reality we continue to evolve the initial concept that we designed with the GP3 [2003]," claimed Preziosi. "So it's not a change in the direction of development, but another step forward in the same direction.

"With the 990 the seat supports and the footpegs were attached to the frame. With the 800 they are both completely separate and on the GP9 the front part is even more dedicated to support and the dimensions become more limited.

"The fact we've used carbon fibre in the production of the chassis is not the most relevant point, it is more the shape that is different from before. Casey's first impressions have been positive. Tomorrow Marco will try it and I hope his feeling with the new bike is better than with the current one," he admitted.

Melandri's best Monday time was 0.3secs under his quickest during the race, set en route to eleventh position, but he was only ranked 15th on the day one testing timesheets.

"We have done a lot of tests with the electronics, set-up and tyres. I've found a rear tyre that gives me a better feeling but we're still a long way from where we need to be. We still need to find something to get back to the kind of feeling I had in China," he warned, referring to his fifth place in Shanghai, the sole highlight of a harsh 2008 season to date.

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