Fiat Yamaha's Valentino Rossi needs to finish only fourth or better in Sunday's Malaysian GP to guarantee his seventh premier class title and ninth world championship overall.Rossi arrived in tropical Sepang with a 38 point lead on teammate Jorge Lorenzo, the only rider with a slim hope of preventing him from taking the crown. Lorenzo killed his championship chances by crashing after ramming Ducati Marlboro's Nicky Hayden in the first turn of last Sunday's Australian GP. Meanwhile, Rossi sped to second behind Hayden's teammate Casey Stoner and added 20 points to his lead. Now Lorenzo can only hang his hopes on winning the final two races and hoping Rossi doesn't score better than fourth in either Sepang or the season finale in Valencia in two weeks time. Though Rossi has made more race mistakes this year than in any recent season, that isn't likely.Rossi is one of only four riders-Lorenzo, Stoner, and Dani Pedrosa are the others-with a realistic chance of winning Sunday's race. Which means that if he finishes, the crown will certainly be his. And when he finishes at Sepang he finishes well. Rossi has five MotoGP wins, two on a Honda and three on a Yamaha, plus a pair of seconds."Yes, so important, because we have the first good match ball for the championship, because after the mistake of Jorge (Lorenzo) in Phillip Island we have a good advantage, but we have to for sure take like a normal race, especially from the practice, because I like a lot this track, great result, great races in the past," Rossi said. "I'm happy, especially because we work well in Phillip Island for all the weekend and my bike for the race work well, so the main target is arrive on Sunday with a good setting. For sure we spend a lot of time during the winter in this track, so we have a lot of data. And we will see."Like I say, I like this track, but also Casey (Stoner) and Dani (Pedrosa) are very fast in Sepang and Jorge (Lorenzo) wants to make a good result for sure after a bad result in Phillip Island." Stoner won here in 2007.Rossi made it clear that the championship, rather than a race win, is the main goal."Yes, for sure, I think that, anyway, is more important think of the championship than of the race, for sure," he said. "So the main target is arrive in the first four if Jorge wins, but we have to try to stay in front of him and try to arrive on the podium. This is, I think, a good result."The always hot and humid weather could well play a part in the outcome of Sunday's penultimate round of the championship. Last year the race was run in 102 degree heat with a track temperature of 108.Joked Rossi, "Last year was 40 degrees in the race and I remember the last laps you start to see black and white."Afternoon showers, which are in the forecast, usually douse the track, but just as quickly dissipate. The hope, for Rossi at least, was for more consistent weather throughout the weekend."I remember a very strange qualifying practice," he said of last year's lone Saturday session, "start with a wet tire, but the surface drying up so quick that at the end we were able to use also the qualifying tire. So we need to be ready, also for the wet condition, but for sure we hope, everybody I think hope, that is a good weather for Sunday. And I think is also the hardest race of the year for all the riders, because the temperature is very high."The weekend is especially important for Yamaha. Though they're guaranteed to win the MotoGP crown for the second year in a row, the company could also win their first ever World Superbike Championship on the same day they may be celebrating Rossi's crown. Yamaha's Ben Spies is locked in a title fight with Ducati Xerox's Nori Haga that will be decided in the final round of the series in Portimao, Portugal on Sunday afternoon.