Davies's promotion was shortlived, however, when Melandri streamed through into turn one on lap 13 and quickly set about bridging the gap to Rea in the remaining five laps.
A series of fast lap times were successful in bringing Melandri onto the tail of Rea as the closing stages approached, but while Rea certainly had the measure of his rival over the majority of the circuit, the lengthy home straight made him easy prey as could do little about to stop the BMW from cruising past well before turn one into the final lap.
Rea attempted to respond, but Melandri's inch-perfect lines meant it would be the BMW rider passing the chequered flag in first position for a result that marks a second win for the manufacturer just two weeks after it celebrated its maiden triumph at Donington Park.
Despite having to settle for second place, Rea – together with Melandri – find themselves well in the fight for the title on 141 and 142.5 points respectively, just 19.5 and 18 points adrift of overall leader Max Biaggi.
Though he has now not won a race since the season opener at Phillip Island, a pair of third places sees Biaggi extend his overall lead. Even so, he was made to work hard for the podium as he fended off the attentions of Davies, the Welshman proving he has come of age at Superbike level with his breakthrough run to fourth position.
Having faded dramatically in race one, Tom Sykes maintained a steadier pace for fifth position, the Kawasaki rider holding off Eugene Laverty after a race-long battle.
Davide Giugliano was another to fare better in race two in seventh place, the Italian finishing ahead of Leon Haslam, who ended a fairly anonymous weekend down in eighth position.
Poor starts once again determined the outcome of Jakub Smrz and Sylvain Guintoli's races, the Effenbert Liberty Ducati pair failing to build on promising qualifying performances to finish a distant ninth and tenth.
Having started 20th, Leon Camier salvaged decent points in 11th, ahead of BMW Italia duo Michel Fabrizio and Ayrton Badovini, while French counterparts Loris Baz and Maxime Berger rounded out the points' paying positions in 14th and 15th.