Following his excellent run to the podium in race one, Giugliano's quest for a double rostrum came to an abrupt conclusion on lap six when he slid out at the final corner to complete a dismal end to the day for Althea Racing.
His demise lifted Haslam up to third place, though Rea would regain the position on lap nine before proceeding to get the better of Sykes for second on lap eleven. Haslam would duly go with him, but while the pair would ride away from their followers, the gap to Biaggi was far too large to bridge.
Indeed, at time Biaggi would lap more than a second faster than his opposition, his advantage eventually stabilising around seven seconds as he cruised through the second-half of the race.
With the home straight all to himself as he crossed the finish line, Biaggi completed a comprehensive second win of the day. In turn, his lead in the overall standings has increased from 18 points to 38.5 points over Rea, while reigning champion Checa finds himself 60 points adrift now.
Fending off the persistent attentions of Haslam, Rea completed a strong podium finish on the Honda to improve his position in the overall standings, while British BMW rider brought home his fourth rostrum of the year in third.
Seemingly escaping punishment for his earlier indiscretions, Melandri held off a determined Ayrton Badovini for a valuable fourth place finish, though the latter will likely rue the mid-race error that allowed his BMW counterpart through and scuppered his podium challenge.
His team-mate Michel Fabrizio
made it a BMW 3-4-5-6 after out-sprinting the Kawasakis to the finish line, Tom Sykes just resisting the increasingly impressive Loris Baz for seventh and eighth, while Jakub Smrz wandered home a lonely ninth.
A race of fairly high attrition, Checa, Giugliano, Guintoli, Eugene Laverty, Leon Camier and Chaz Davies all crashed out of top ten positions during the race.
As such, Matteo Baiocco was able to turn in a positive tenth place finish for the wild-card Barni Ducati team, the local rider fending off Maxime Berger, Hiroshi Aoyama and Niccolo Canepa.
FIXI Crescent Suzuki duo John Hopkins and Leon Camier picked up the final points, the former losing time with a run across the gravel on lap one, while the latter was recovering from a crash on lap six.