ROME, Italy - Seven-times World motorcycle champion Valentino Rossi has refused to write off his 2012 title chances with Ducati but does admit it will be tough.Rossi, now 32, endured a torrid 2011 season, his first with Ducati, in which he finished seventh in the championship and didn't win once - for the first time in his 15-year career - though he did make the podium once. And he never scored pole, that for the first time since 2000.'HAVE TO BE REALISTIC'Tthe Italian admits that toppling Casey Stoner and Jorge Lorenzo may be beyond him on the Ducati but he was not prepared to begin the season defeated."I don't want to take myself out of the running before the championship even begins - but you have to be realistic," he said. "We know we have 1.5sec a lap to make up. Our aim has to be to close in on Honda and Yamaha and only by doing so will we be able to fight for success."Rossi said he was hampered by injury in 2011; he's not expecting a problem in 2012. "Last year I had to take into account my shoulder problems until Barcelona (race five of the season) but I'm in shape for this season."My hunger to win is undiminished even though I belong to another generation and have to take into account younger and more battle-hardened rivals than I had in the past."NINE WORLD TITLESRossi dismissed suggestions that he might retire rather than risk becoming an also-ran. "I want to make Ducati strong before I stop," he said. "I would like a new two-year contract with Ducati, maybe my last, then I'll think about how to have fun."Rossi has won nine World titles, including 125cc and 250cc categories. He joined MotoGP in 2000 and 2011 was the first season in which he failed to finish in the top three.