Up front, Byrne was stalking Hopkins carefully, launching a magnificent pass up the inside of Coram, one that caught his rival unawares and dropped him to second position with just a lap remaining. Even so, having snatched victory from Hill on the final lap of race one, Hopkins looked confident as he sized up Byrne for a re-pass.
However, his rather late dive down the inside of Byrne at Oggie's would prove somewhat ill-judged, the pair making contact and becoming hooked up together as they rounded the bend. Both were sent wide on the exit, with the close-following Kiyonari slipping beneath the pair to grab the lead.
Hopkins resumed in second place, but was promptly swallowed up by Brookes, who also pushed his way past into the Bombhole. Byrne, meanwhile, was forced to take a trip across the grass, dropping him to fourth.
The drama duly allowed Kiyonari to score a somewhat unexpected victory, the three-time title winner proving he is still a championship contender despite his lacklustre recent form.
Brookes held on for second to record his first podium result for Relentless by TAS Suzuki. More significantly, however, his decent points' haul – coupled to problems for others – sees him leap from 12th to the all-important sixth place in the overall standings.
A slightly bashful Hopkins collected the points for third, the American apologising for the outcome of his actions, but maintaining his right to have attempted a pass. A frustrated Byrne crossed the line fourth, but retains a comfortable championship advantage.
Behind the drama unfolding up front, Michael Laverty came home a quiet fifth place on the Swan Yamaha, ahead of Martin Jessopp, who claimed his first top six finish since the leg injury that ruled him out of most of the 2010 season.
Loris Baz picked up seventh, capitalising on Jon Kirkham's crash out of the position with two laps remaining, while Chris Walker completed a second top ten finish of the day in eighth.
Ian Lowry's ninth marks the first top ten finish for the Buildbase BMW team this year, while Jake Zemke notched up his maiden EVO class victory in only his second meeting with an excellent run to tenth place overall.
In the lower reaches of the points, Gary Mason, Dan Linfoot, Glen Richards, Barry Burrell and Patric Muff completed the top fifteen.