Quickly stalking Haslam, Smrz waited just one lap before pouncing under Starkey's Bridge to nose his Effenbert-Liberty Ducati to the front of a WSBK race for the first time in his career.
Far from intimated, Smrz proceeded to pull away, proving the only rider to lap in the 1min 29secs as he left Haslam to robustly defend second position from an increasing number of riders.
Further back, following their rather public spat after Superpole yesterday, Biaggi and Melandri appropriately found themselves alongside one another on the circuit, the pair proceeding to embark on an enjoyable – if at times tense – tête-à-tête. Repeat passes on one another raised some gasps, though it would take a failed lunge by Biaggi on Haga for fifth at Redgate for Melandri to move ahead decisively.
Immediately pouncing on Haga to claim fifth, with Biaggi unable to follow his rival through, Melandri was given the breathing space to begin attacking the lead group.
Biaggi, meanwhile, was getting caught up in battles with riders behind him, Rea announcing his presence with a block pass at Melbourne, allowing Checa also through, the trio running seventh, eighth and ninth now.
Melandri, on the other hand, was picking off those ahead of him steadily, taking Sykes for fourth on lap 11, Camier for third on lap 15 and Haslam for second on lap 16.
Leaving him with just seven laps to reel in Smrz, Melandri faced a tough challenge after the 27-year-old had put a good 2.4secs gap between himself and those behind.
However, fading tyres had left Smrz vulnerable and as Melandri took tenths off his margin with every lap, it was little surprise to see him cruise past on the penultimate on the run to the Esses.
It meant Melandri led just a single lap of the race, but it would be the decisive one, the Italian scoring his first world championship win in five years. It also marks Yamaha's fifth straight win on UK soil.
Though disappointed to be denied a first WSBK win in 110 starts, Smrz was pleased with second position, not least because it marks only his second podium finish in more than four seasons of trying.