However, there had been no real increase in the occasional drop of rain that was falling and so no rider took the opportunity to pit for a spare bike... but 8 laps later the rain suddenly increased around turn one - race leader Gibernau was the first to find it and spiralled out of the lead after losing the front even before reaching the apex.
The Spaniard ran to his toppled machine but it was dead, prompting screams of frustration from within the watching Movistar pits and leaving the already injured #15 to walk away with his head shaking in disbelief. All that effort for nothing. But Sete wasn't the only victim as Hopkins fell from a fighting eighth place soon after, almost certainly for the same rain related reason.
Previously, the race would almost certainly have been stopped by either race control or the riders themselves, and then restarted using the order from the end of the previous lap - allowing both Gibernau and Hopkins back in.
But that is the past and Gibernau's demise handed Barros a safe lead, which he would increase to seven-seconds over the battling Rossi and Biaggi with 8 laps to go, by which time the rain had eased off once again. Meanwhile, Edwards and Melandri were still fighting over what was now fourth - and had now been caught by Checa.
Then, with just five laps to go, the drama went up a notch once more as the rain began falling heavier than ever – and again nobody dared pit because the 40ish seconds lost changing bikes just wouldn't be recovered before the finish, despite lap times dropping by around 7-10secs.
Edwards was the first to fall in the 'second' shower, but remounted quickly to only lose two places (to Melandri and Checa) while Rossi just clung on to the other factory M1 after almost losing the front.
Meanwhile, Barros rode though it all as if on rails - but had clearly eased his pace and with two laps to go his lead over a charging Rossi had dropped to 5.5secs.
Alex began his last lap with Rossi visibly closing but, despite a brief wet white line scare, the jubilant Brazilian went on to end his two-year plus win drought by 2.7secs over the Italian superstar, while Biaggi cruised to third a further 3secs back for his first factory Honda podium.
It was literally a perfect weekend for Barros, who should have been competing at his home event had Rio not been cancelled. Nevertheless, he could hardly have asked for more; leading all six on-track sessions to claim his first win since Valencia 2002, when he was also riding for the Honda Pons squad.
29-seconds behind Barros, Melandri and Checa duelled right to the flag, with Checa trying a last lap outbraking move but running wide and allowing Marco to follow up his Jerez third with an Estoril fourth. Edwards would cross the line 14secs behind the pair for sixth, while Hayden, Nakano, Capirossi and Xaus completed the top ten.