Kenny Roberts Jr. and Valentino Rossi both had cause for celebration in Rio when Rossi won the race and Kenny the 500cc World Championship.

At the start pole sitter Max Biaggi made a poor get-away and dropped to tenth while Tadayuki Okada stormed into the lead from the second row of the grid. Gary McCoy, winner of the two previous GP's, also made a good start rising from thirteenth to fifth at the end of the first lap. Roberts meanwhile was lying in seventh.

Local hero Alex Barros, desperate to win in front of his home crowd, took the lead from Okada at the end of the second lap, with McCoy now up to third. The order remained the same until lap seven when McCoy, visibly pushing hard, squeezed past Barros with Rossi seizing the opportunity to follow in his wake.

By lap nine the leading trio of McCoy, Rossi and Barros had broken free from the rest of the field, with McCoy riding on the edge to stay in front - his bike visibly sliding into the corners under breaking and wheel spinning out under acceleration.

Rossi on the other hand was riding a smooth and controlled race and looking like he had every chance of winning - so long as he picked his moment. Roberts' Telefonica Suzuki team clearly thought the same and decided to tell Roberts of Rossi's position, via his pit board. Rossi eventually found a way past on lap thirteen, immediately building a comfortable gap back to Barros.

By this time Roberts was having a bad race lying in tenth position, he later explained, "It was difficult. I couldn't push too hard and risk falling down", this meant that the more aggressive riders were overtaking him. Finally with two thirds of the race gone Roberts began working his way back up through the pack to seventh, past his teammate for next year Sete Gibernau with Regis Laconi holding the vital sixth position.

Roberts' move came with five laps to go when he slipstreamed past Laconi on the one kilometre back straight. Once into sixth and with fifth position (Biaggi) some way up the road Roberts was content to hold station for the remainder of the race.

At the front meanwhile, Barros was beginning to pressure Rossi, urged on by the Brazilian crowd, and set the fastest lap of the race with three laps to go. McCoy, running with a softer front tyre than Rossi and Barros, slipped further back and into the clutches of Abe and Biaggi, with whom he fought out the remaining laps.

Rossi responded to Barros' challenge, setting a new fastest lap himself and came home to win his second 500cc Grand Prix in only his first year in the class.

Race winner Rossi and new World Champion Roberts celebrated in style on the slowing down lap by stopping and doing burnouts together, before Roberts' mechanics hastily stuck a number one on his Suzuki.

An ecstatic Roberts said afterwards "I've dreamed about being 500cc champion since I was a kid. It's been a 27-year season to get to this point. The championship means everything to me." Father Kenny senior added, ''Winning the 500-class title is a hell of an achievement. Not many people can say they've done that. He's become one of a great series of champions from America."

Team manager Garry Taylor explained how the championship had been a two-year plan, "The first year was to adapt the bike - Warren Willing and the race department interpreting his feedback and getting modifications to the race track as soon as possible. He finished second overall, so we were on the right track. The second year was to win the title."

Rossi put a brave face on any post race disappointments he may have had at the loss of the championship and thought instead about how and the team he had improved over the last few races stating "It was a very important win". Alex Barros second in front of his home crowd said, "I am very happy its my first podium in Brazil".