Valentino Rossi has predicted his Fiat Yamaha team-mate Jorge Lorenzo will provide his stiffest opposition as the Italian continues his progress towards retaining the FIM MotoGP World Championship title in Indianapolis this weekend.

Rossi, who won the last round at Brno in the Czech Republic after Lorenzo crashed, heads the series standings by 50 points - but is not taking winning the championship for granted.

Rossi admitted: "As I said in Brno, it would be stupid for us to relax and consider the championship won - anything can happen and we know that Lorenzo will be very strong this weekend and determined to make up for the last two races. We must keep focused."

Last year's race at Indianapolis was hit by a hurricane, and Rossi hopes the weather in America is better this weekend.

He added: "Every year is a different story, so we won't know where we are until we start our work on Friday afternoon.

"Last year I had a great win but, like everyone, I really hope that was the only hurricane we ever have to race in and that this time the conditions are more 'normal'."

Lorenzo, who earlier this week signed a deal to remain with Yamaha for the 2010 season, is also eager for better conditions at Indy on Sunday.

"Last year was strange, maybe we should have finished earlier because Hurricane Ike was pretty strong; this time I hope everything will be a little bit easier," said the Spaniard.

"I am feeling confident because I've felt good in the last races, riding very fast since the beginning of the weekend, despite what happened on Sunday.

"I am not thinking about the championship any more but I would like to win a race again after more than three months, especially here in Indy when it's the centenary of the track. It's a busy two weeks, with Misano straight after, but we're ready."