Alastair Seeley secured his first British Superstock 1000cc win of the season by edging out fellow Northern Irishman Josh Elliott at Oulton Park.
Tyco BMW rider Seeley was 0.208 seconds ahead of Fermanagh man Elliott, the result taken after 11 laps after a crash caused the race to be stopped.
Morello Kawasaki rider Elliott leads the series on 65 points, with Seeley, from Carrickfergus, third on 52.
Glenn Irwin finished second and fourth in the two Supersport 600cc events.
The Gearlink Kawasaki pilot came home behind race winner, Triumph-mounted Luke Stapleford, in Sunday's sprint race.
Andy Reid from Jordanstown was fourth and Portadown's Marshall Neill 14th in the race, which was red-flagged with two laps remaining.
Irwin and Reid both enjoyed spells at the front in the feature race, which was ultimately won by Jake Dixon. Reid ended up third and Irwin fourth after a thrilling four-way battle at the front.
Irwin is third in the championship standings on 95 points, 16 behind leader Stapleford and 15 in arrears of second-placed Kyle Ryde.
The Moneymore-based Tyco BMW outfit enjoyed further success, with Tommy Bridewell winning the opening Superbike race, in which Michael Laverty was eighth.
Laverty improved to fourth in the second outing of the day, which was won by Scot Stuart Easton.
After his success, Seeley said he would now head to next week's North West 200 international road races "brimming with confidence".
"We have had some bad luck in the opening few rounds of the series but hopefully this will mark a turning point in my season," said the 35-year-old.
Castlerock's Marty Nutt was runner-up in the Ducati TriOptions Cup event and is second in the series after three rounds.