Guy Martin edged out Bruce Anstey in a thrilling Superbike race at Thursday's Dundrod 150 meeting staged as part of the Ulster Grand Prix bike week.
Lincolnshire rider Martin passed New Zealander Anstey early on the final lap as he won by .24 of a second.
Michael Dunlop took third with the top six completed by Dean Harrison, Lee Johnston and William Dunlop.
Fermanagh man Johnston won the earlier Supertwins event ahead of Connor Behan and Keith Amor.
In the Superbike race, Martin produced the fastest lap with a 133.31 mph clocking on his final circuit while the top four all produced laps over 133 mph.
Johnston took the earlier Supertwins victory as he finished two second ahead of English man Behan who rides for the KRM Kawasaki team.
Behan's team-mate Amor completed the podium positions with another Lincolnshire man Ivan Lintin setting a new event lap record of 118.734 on the way to finishing in fourth.
Carrickfergus man Glenn Irwin, currently fifth in the British Supersport short circuit series, took fifth spot on his road racing debut.
Englishman James Cowton won the ultra lightweight event with his compatriot Christian Elkin taking the lightweight victory in a concurrently run race which had to be re-started after a serious accident involving an unnamed rider.
The rider was taken to the Royal Victoria Hospital in Belfast as action had to be halted at the Dundrod circuit for around an hour and was later said to be in a critical condition.
In the final class of the day, English newcomer Peter Hickman won the Challenge event by 23 seconds from Alistair Kirk.