Valentino Rossi defied a hurricane to become the most successful rider in premier class Grand Prix history.

Rossi took his 69th Grand Prix win in the top class to break Giacomo Agostini's record and open up a massive 87-point lead over Marlboro Ducati rider Casey Stoner in the standings with just 100 points left to win.

It was a remarkable ride - his fourth win in a row - as the tail of Hurricane Ike caused havoc to the first MotoGP at the historic Indianapolis circuit.

Torrential rain had blighted the whole weekend and a downpour which forced the 250cc race to be postponed almost curtailed the race altogether.

The riders had a meeting after Friday's practice session where it was agreed that they would not race in similar conditions after the entrance to turn one was left under several inches of water.

But conditions let up to allow the race to go ahead as scheduled on a wet but drying track.

Stoner got a good start to lead into turn one while Rossi went backwards to lie in fourth but home favourite and 2006 champion Nicky Hayden soon took the lead.

Rossi soon scythed his way up to second before the rain started falling again with 18 laps to go.

The Italian then made a bold move to take the lead on lap 13 before the weather really took a turn to the worse.

Massive winds hit the circuit to blow debris across the track and demolish several hospitality tents and ensure that the surface water changed position on a lap-by-lap basis.

But while the rest of the field struggled just to keep on two wheels in treacherous conditions Rossi was somehow able to open up a six-second lead before the race was sensibly red-flagged with seven laps remaining.

Hayden was second on his Repsol Honda with Rossi's Fiat Yamaha team-mate Jorge Lorenzo third.

Stoner was fourth and British rider James Toseland was out of the points in 18th.

Rossi said: "Those were the worst conditions I've ever raced in during my career.

"With a new track and a new surface it is difficult enough but then there was a lot of water and the wind.

"The bags and beer cans were on the track and it was so inconsistent. The wind was incredible.

"Every lap it was blowing in a different direction. I didn't want to put my hand up and request for the race to be stopped because I was winning.

"But every lap I was hoping for the red flag and was very relieved to see it." Earlier 15-year-old Scott Redding continued his superb season with a fourth-placed finish in the 125cc race and fellow British teenager Bradley Smith was eighth.