From here, the pendulum between the top three swung continuously, the gap increasing and shrinking as they either worked together or tripped over one another.
Eventually, Biaggi would work his way back up to second place after a late-braking manoeuvre on Rea at Lycee was duly rewarded, Rea being forced to concede on the tarmac run-off area in a failed attempt to repel his rival.
Allowing Biaggi one last go at taking the win, Haga would nonetheless keep things very much under control, taking the win by just over a second from Biaggi, who in turn made it a double podium for Aprilia, and Rea in third.
Spies, meanwhile, laboured home in fourth after rapidly dropping off the pace with an apparent problem on his Yamaha R1. Having rallied early on, Spies was more than two seconds behind the leaders when he began to drop back more noticeably, the visibly frustrated race one winner finishing well adrift by the chequered flag.
Nonetheless, the result could prove to be important in the long-term as it keeps Spies to within ten points of Haga in the standings. Crucially, this means that if Spies wins both races at Portimao – one of the few circuits on the calendar he knows – and Haga finishes just behind him in second position, his greater number of wins (a potential 15 to Haga's eight) would see him win the title despite finishing the season equal on points.
Indeed, luckily for him, Spies was unable to be overhauled by Leon Haslam, who posted his second top five finish of the day for Stiggy Racing after yet another lonely performance.
Sixth position fell to the person he is tipped to be replacing at Suzuki next season, Yukio Kagayama, the Japanese rider producing his most convincing race day performance since Monza to eventually prevail over Shane Byrne following a race-long battle.
Eighth place for Kagayama's team-mate, Karl Muggeridge, gave the team further reason to be pleased as the Australian posted his first top ten result with Suzuki and his best finish since Miller Motorsports Park last season.
Ninth place was originally set to go the way of Leon Camier, but the young Briton was once again eliminated by a technical issue, leaving him with a bitter double DNF on his debut with the Aprilia team.
Instead, Carlos Checa
assumed the position, having recovered from an early delay when circumnavigating Michel Fabrizio's fallen Ducati, ahead of Troy Corser
and Fonsi Nieto, while Ruben Xaus
in 12th ensures BMW's collects its biggest points haul over a single weekend since entering World Superbikes.