Tyco BMW's Christian Iddon won the first of the weekend's Superbike races today at the Sunflower Trophy races.
Almost half the competitors either did not start or pulled out after the first lap in the difficult conditions due to standing water around the County Down circuit.
The Stockport rider edged out this year's National Superstock 1000 champion Richard Cooper, taking the chequered flag by 0.883 seconds.
Eunan McGlinchey finished in third some 34 seconds behind the Buildbase Suzuki man.
In the afternoon's other races Michael Mackinnon, Jack Oliver and Paul Demaine were the top three in the pre-injection race.
Mackinnon also had a win in the Supersport/Superbike Cup race with Aaron Uprichard and Jonathon Watt second and third.
Cameron Dawson continued his winning form in the Supersport 300/Junior Cup/Young Guns opener.
Lee Crawford won the Sidecar race with Peter O’Neil and Michael Kirkup second and third.
Veteran rider Jeremy McWilliams qualified quickest for tomorrow's Supertwin race and Richard Kerr is on pole in the Supersport class.
The feature Sunflower Trophy Race and a full programme of 12 other races will complete the weekend's racing tomorrow.