Rossi unrolled a huge poster which featured a picture of every single one of his 100 victories, starting with Brno in 1996. At the end of the poster was a huge number 100 and Rossi was then given a flag bearing that number to carry for the remainder of the slow down lap, cheered on by the 96,000 fans.
Rossi's 100 grand prix wins are divided 74 (500cc/MotoGP), 14 (250cc) and 12 (125cc) and he is now five points clear of Lorenzo in the 2009 world championship.
The only other rider to claim 100 grand prix wins is fellow Italian Giacomo Agostini, a winner of 122 races in all classes. Rossi already holds the all-time record for premier-class race wins.
"The hero of today is Valentino," said Lorenzo.
Having been unable to threaten the factory Yamahas, a disappointed Stoner took his fifth podium of the season by finishing a distant 23 seconds behind Rossi. Although he had not hinted at a physical problem before the race, Stoner - who fought sickness in Catalunya - went to the medical centre straight after the podium ceremony.
The injured Pedrosa crashed out when he lost the front of his RC212V at turn one at the start of lap five - and Repsol Honda team-mate Andrea Dovizioso
suffered exactly the same fate, at exactly the same corner, while also holding fourth on lap 10.
Honda has now gone 18 races, over one full season, without a MotoGP win.
Dovizioso's exit promoted Edwards to fourth and the Monster Yamaha Tech 3 rider equalled his best finish of the season by crossing the line six seconds from Stoner. Edwards is now equal fifth with Pedrosa in the championship.
After an excellent start, Chris Vermeulen
rode a strong but lonely race to fifth position for Rizla Suzuki, his best result of the season so far.
Whilst the leading positions became quickly strung out, battle of the race was the contest for sixth between James Toseland, Mike Kallio, Randy de Puniet, Nicky Hayden, Alex de Angelis, Loris Capirossi
and Toni Elias.
Positions changed constantly, but rookie Kallio overtook Toseland for sixth on the brakes during the penultimate lap - only to lowside at high speed through the final turns of the final lap, hurting his hand in the process.
Elias then lunged for Capirossi forcing them both wide at the final chicane and allowing Toseland's Tech 3 Yamaha to regain an equal career-best sixth, by 0.196sec from the top Honda of Randy de Puniet.