Meanwhile, up front Bayliss – who was being shadowed by Gibernau – was starting to slide the rear of his bike more and more on the notoriously tyre eating circuit, and it was no surprise when (on lap 10) he ran slightly wide after a rear wheel slide under braking, allowing the Telefonica machine to take the lead.
Despite his best efforts it wasn't long before Biaggi and Rossi had caught the Desmosedici, and it would be another mistake which gifted Biaggi second – but Rossi was soon to find it wouldn't be that easy for him.
The World Champion made his move soon after Biaggi, but must have been more than a little surprised when Bayliss retaliated by sticking his front wheel back under the Repsol Honda at the next turn... Rossi held firm, but then ran wide himself (at the same place he lost the 2002 race to Ukawa) – giving Bayliss the position back. That wasn't in the script.
By now Rossi was looking more aggressive than he's ridden for a long time, and with his RCV's rear wheel skipping under him, he went back ahead of Troy. But rather than setting about dropping the Ducati and closing down the 2sec gap to Biaggi, Vale slipped up again and Bayliss was only too pleased to grab the place back.
The five lap battle between them came to an end on lap 18 when Rossi made what would be his final pass on the Australian, who now just didn't have the rubber to hold a tight line and keep the throttle pinned.
By this stage Gibernau had a 2.5secs lead over Biaggi, with Rossi needing 1.5secs to catch the Camel rider.
Behind the top quartet, Abe, Ukawa and Barros were fighting just as furiously for fifth, with Norick surprising many by catching then passing his quick starting temporary team-mate Checa (now eighth, behind Hayden) to be top Yamaha heading into the final third of the race.
Man on the move in that group was Barros – clearly eyeing the top M1 title – who carved his way past Ukawa with 7 to go, then made short work of Abe, but Bayliss would be out of reach.
Instead, up front Rossi and Biaggi were beginning to reel Sete in, and the alarm bells were raised in the Gresini pits when Rossi – clearly the fastest man on track thanks to his harder (dual compound) tyres - took advantage of a Biaggi error to take second with five laps to go.
Over the next four laps Rossi cut the gap to Gibernau from 2.4secs, to 1.9secs, then 1.2secs, then 0.5secs at the start of the last lap. The tension was exhaustive in itself as all but Rossi's Repsol team willed the Catalan on.
With the Gresini team barely able to watch, Rossi – now riding with his usual smooth style – cut 0.2secs out of Gibernau's lead in the first sector, but Sete fought back through the fast middle part of the lap, and despite his RCV squirming underneath him, the #15 held firm through the final sequence of corners to take one of the most emotional victories in MotoGP history.