Melandri finished the season with back-to-back wins

Rossi began brightly from his worst grid place of the season, 15th, but never caught the leading pair.

Nicky Hayden was a close second, with Rossi third and Carlos Checa fourth.

Home favourite Sete Gibernau's day ended in disappointment as, having started from pole, engine problems forced him to pull out on lap four.

Melandri, who won his first Grand Prix last time out in Turkey, made it back to back wins as he came home in a time of 46 mins 58.152 secs.

I tried to shake off Hayden but he rode really well. But the last few laps went perfectly Marco Melandri

He beat pole sitter Gibernau off the grid and led from start to finish, with only Hayden coming close to challenging him for the lead.

As soon as the bikes were off the grid Rossi set about improving his position, and by the end of the opening lap he had moved up to eighth place.

But he could never quite catch up with the leaders and ended up coming home three seconds behind second-placed Hayden.

The final placings meant the Italian finished as runner-up in the championship behind Rossi, with Hayden in third place.

"I was thinking of the championship race more than today's race," said Melandri afterwards.

"I tried to shake off Hayden but he rode really well. But the last few laps went perfectly for me."

Rossi said his poor grid placing, caused by a crashing in qualifying on Saturday, had ended any realistic chance of victory.

"I made a mistake yesterday and we struggled too much with the bike," he said.

"We understood the problems this morning but it was too late to try and win.

"I made a good recovery but we need to make a better effort next time."

Valencia MotoGP result (Sun):