Having halted Ben Spies' victory run in the opening race at Valencia, when the superstar rookie crashed out of third, Noriyuki Haga comprehensively beat the American in a straight fight during race two for his first double victory of the season.
After three rounds, Haga and Spies have now taken three wins each, but Haga's consistency - the Ducati Xerox star has finished first or second in every race - has put the Japanese into a solid 40 point title lead over the AMA champion, who scored no points in race one at Phillip Island in addition to his Valencia DNF.
Spies once again lost ground from pole at the start of race two, his R1 raising its front wheel too much off the line, but Haga faired little better and the two title contenders found themselves fourth and fifth during the opening lap - when Spies saw an early attempt to overtake Haga firmly rebuffed by the #41.
The pair then worked their way forwards past Regis Laconi (DFX), Michel Fabrizio (Xerox) and Max Neukirchner (Alstare) - Haga hitting the front on lap five, with Spies into second soon after.
Haga was only 1.2sec ahead of Spies at that stage, but the Japanese edged ever further away from the #19 and - despite a slow final lap - crossed the finish line a distant 5.105sec in front of the Yamaha rider.
Spies in turn faced little pressure from behind, with third placed Fabrizio instead having his hands full defending the final podium position from Laconi, which the Italian claimed by less than 0.2sec from the satellite Ducati rider.
Leon Haslam turned his tenth position on the grid into two satisfying fifth place finishes for Stiggy Honda while Neukirchner, third behind Haga and Fabrizio in race one, dropped back to a disappointing seventh in race two.
Home star Carlos Checa, who retired from race one, salvaged some pride with sixth in race two for Hannspree Ten Kate Honda.
As in race one, Tom Sykes and Max Biaggi worked their way forwards from an unrepresentative 17th and 18th on the grid - Biaggi claiming eighth position on the lone Aprilia with Sykes tenth on the second factory-backed Yamaha.
Ryuichi Kiyonari finished between the pair in ninth for Ten Kate with another BSB champion, Shane Byrne, ninth and eleventh on Sunday.