Ryan Farquhar denied fellow Northern Irishman Alastair Seeley a clean sweep of the time sheets during the first qualifying session at the Relentless International North West 200.
Farquhar, an accomplished Superstock rider, held off the Tyco Suzuki British Superbike rider by less than half a second to set the fastest time in the production-based class on his KMR Kawasaki ZX-10R.
Ulsterman Farquhar's fastest lap was 117.55mph, narrowly keeping him ahead of Seeley, whose best speed for the 8.9-mile circuit was 117.34mph.
The Superstock session was stopped prematurely before a massive hail shower, but the organisers were otherwise fortunate with the weather, running all sessions in predominantly dry conditions.
Isle of Man TT legend John McGuinness rounded off a solid opening day at the Relentless International North West 200 as he was third fastest on the Padgetts Honda CBR1000RR, two seconds down on Farquhar.
Northern Ireland's Stephen Thompson (115.04mph) was fourth fastest from Kiwi Bruce Anstey (115.03mph), who had an otherwise quiet day by his standards on Clive Padgett's machines.
Cameron Donald was sixth on Wilson Craig's machine at 114.89mph.
Farquhar will start Thursday's Supertwin race as the hot favourite, but it was Ulsterman Adrian Archibald who posted the fastest time on his 650cc Kawasaki ER6 at 104.35mph.
Michael Rutter was second fastest on one of Farquhar's KMR Kawasakis at 104.03mph ahead of James Hillier on the Bournemouth-backed Kawasaki (103.85mph) with Farquhar fourth at 103.84mph.
Ex-Grand Prix winner Jeremy McWilliams, who is making his North West 200 debut in the Supertwin class, was ninth fastest with a best lap at 100.23mph.
The Supertwin race will be held following final practice on Thursday evening along with the first Superstock race.
Five races complement the main programme on Saturday, including two Superbike and Supersport events and the second Superstock race.