Ten of his rivals slid off their bikes as rain lashed the British Grand Prix on the Leicestershire circuit, but Rossi kept his Gauloises Yamaha upright to record his seventh win of the season.
"That was not like riding a motorcycle, it was like driving a boat," the 26-year-old Italian said after overwhelming the Brazilian Alex Barros and the American Kenny Roberts in the closing laps of the race.
"The track didn't have any grip, and it was very cold. I span a lot at the start and lost positions. But I pushed a lot in the lap when I overtook Barros, and it was a fantastic victory."
That was typical Rossi understatement. With a lead of 79 points over Honda's Marco Melandri in the points table, Rossi could have treated this skating match as an opportunity to play safe.
But the greatest entertainer on two or four wheels put on a show that thrilled the 75,000 fans. And as he crossed the line, Rossi stood up on the footpegs of his bike and played an imaginary violin to mark the drama of his performance.
"Valentino had the confidence and the bravery to take off, and I didn't have anything to match him," Roberts said. Roberts eventually claimed second place in a great day for Bridgestone tyres, which have struggled to match Michelin on dry tracks this year.
Colin Edwards, the "Texas Tornado", splashed his Gauloises Yamaha into fourth place to move into third place in the championship table, and Carlos Checa and Loris Capirossi completed the top six placings on their Bridgestone-shod Marlboro Ducatis.
The deluge gave Britain's Shane Byrne the chance to shine on his underpowered Proton KR. From 18th place he weaved into sixth after only four laps, but his charge ended when his front wheel slipped from under him.
Eleven riders crashed in the 125cc race, but Dan Linfoot, 17, from Knaresborough, Yorkshire, climbed from 34th place to finish ninth in his first grand prix.Reuse content