Keith Farmer moved closer to the British Supersport title with victory in race one at Caldwell Park.
The Clogher rider was challenged by Andrew Irwin for the win, who crashed out while leading the race.
Dubliner Jack Kennedy also failed to finish with a mechanical issue, which hands Farmer a 58-point lead at the top of the standings.
Eglinton rider David Allingham finished third, with Ben Currie splitting the two local riders in second.
In qualifying for the British Superbikes, Carrickfergus rider Andy Reid put in an impressive performance to post the eighth fastest time for the two races on the main day of action at the Lincolnshire circuit.
Michael Laverty qualified in 11th, with Glenn Irwin down in 16th place as he continues to struggle with an arm injury sustained at Knockhill in June.
In the Ulster Rally, Keith Cronin took victory by 56 seconds from Swede Frederik Ahlin and Carryduff's Jonny Greer.
William Creighton put one hand on the Junior British Rally title with his second victory of the year after Claudy's Callum Devine and Letterkenny driver Marty Gallagher both retired with mechanical issues.
In the World Rally Championship, Kris Meeke was forced to retire form the second day of running on Rally Germany with a suspected water pump problem.
The Dungannon driver was already out of contention after being handed a 10-minute penalty after clipping a barrier and failing to finish the first stage.