Nine-times World MotoGP champion Valentino Rossi has slammed MotoGP as "boring" and called for a change to the sport.Rossi said: "Now is the worst moment in MotoGP since I joined in 2000. It is the most boring moment. Races are quite bad and it is very difficult to stay awake."Spaniards Jorge Lorenzo and Dani Pedrosa have dominated this year's championship, winning 12 out of the 16 races so far between them.NEED A CHANGEDefending champion Casey Stoner, who is retiring at the age of 27 in November, 2012, is the only other rider to win this season and seven-times MotoGP champion Rossi believes the sport needs to change."You look at Moto3, the races are very exciting, Moto2 is fantastic and then MotoGP is boring. So they have to change the product."Rossi, 33, hopes he can get back to winning in 2013 with Yamaha.He won four World championships with Yamaha before leaving for Ducati at the end of 2010, but has not won in the last 37 races."This is not the time in my career to be struggling every weekend like this," said Rossi, who has managed just three podium finishes in his two seasons for Ducati with his last win in Malaysia in 2010. "It will be difficult but I think that I have the potential to win some races next year. It is a great pity for me at Ducati. It was a dream, it was a great and important bet to try and win for Ducati but unfortunately we have no way. It has been two very difficult seasons."We try lots of things but we were never able to fix the problems. We had some good races and a few good results but not what everyone expects. We lose the bet."ROSSI AND LORENZORossi will be second rider in his Yamaha team next season, as he partners Lorenzo, who is on course to win his second championship this season."I am at a certain age and I don't know how many years I will continue in MotoGP, so I have to race with the best bike that I can."Fortunately during my career I have won more or less everything so I need to enjoy it to have the right motivation."I need to arrive at the circuit every weekend with the chance to fight for the victory. It will be difficult but that is why I change teams."Rossi won the 125cc championship in 1997 and the 250cc championship in 1999 before moving up to MotoGP where he was world champion seven times between 2001 and 2009.