After an optimistic debut test on the all-new Desmosedici GP12, Valentino Rossi's 2012 MotoGP hopes took a seriouไs knock at this week's Sepang return.

Fifth fastest and 1.22sec from Honda's Casey Stoner after the fဣirst test, Rossi dropped to tenth place during the final pre-season Malaysian trip.

The only positive was that the gap to Stoner - again fastest - was cut to 💞1.07sec, but that was of little co🧸nsolation to the seven-time MotoGP champion, preparing to start his second season at Ducati.

"It has been quite🔥 negative," said Rossi, talking in the Sepang paddock as storm clouds gathered overhead. "The only positive is that the distance to first place is a bit less, but unfortunately our position is a lot worse.

"Being just behind the factory Hondas and Yamahas after the🌃 first test was positive, but everything we tried here - especially to fix our bigge🎃st problems - didn't work.

"We are closer to the top, but now we also have the Monster Yamahas and satellite Hondas in front of us. We are very worried for this reason especia♋lly.

"The new electronics worꦉked well, and helped in the straight, but I'm too slow on corner entry and not able to keep the right corner speed. I also have some movement in acceleration.

🌳"We are not very, very far - but 0.6sec i🔴n the pace is quite a lot."

Rossi๊ explained that his biggest difficulty is understeer, which forces him to use the brakes too much, sapping his corner speed.

But Rossi maintains the GP12, which features Ducati's fඣirst aluminium twin-spar frame, is still an improvement over last year's troubled carbon fibre then part-aluminium 800cc machine, with which he took just one podium finish.

"I thin♚k we have imp🗹roved from last year because we had two or three moments today where for sure with last year's bike I would have crashed!" he smiled. "But it is not enough. The character of the bike from this point of view remains very similar."

Adding to the mystery is that Rossi feels the GP12 responds mor🥃e normally to set-up changes thඣan its predecessor.

"Now when we make changes the bike is quite precise and the answer from꧃ the bike is more normal, comparedꦕ to last year, but unfortunately we don't fix nothing."

Rossi, who admitted there is no obvious solution, explained: "Unfortunately with this bike I'm not able to go faster and faster, like the guys on the other 𒅌bikes, and we have to understand why."

Despite Rossi's problems, Pramac Ducati rider Hector Barbera -꧋ riding the earlier 'Valencia-spec' satellite GP12 - put in a strong final day lap time to repeat his sixth place at the first test and closed the gap to Stoner from 1.322 to 0.🐠768sec.

Rossi's team-mate Nicky Hayden was a fraction behind the Italian in eleventh, having struggled with cha🀅tter and corner exit rather than corner entry. Hayden was more optimistic than Rossi, since his lack of track time at the first test means he still has plenty of ideas and settings to work through.

Thꦅe third and final pre-season test will take place at Jerez, Spain from March 23-25.

"Now we go to Jerez, another track and another temperat🦂ure and try to understand where we are. And then we see," said Rossi.