Michael Laverty finished second and third in Sunday's British Superbike round at Donington Park.
The Samsung Honda rider from Toomebridge is fourth in the series and 21 points behind leader Tommy Hill.
Moira's Ian Lowry crashed in the opener and struggled to 16th in the second race to lie eighth in the standings.
Clogher rider Keith Farmer leads the National Superstock 1000cc championship by nine points after finishing sixth in Sunday's race.
Northern Ireland's Glenn Irwin was fourth and fifth in the Supersport event.
Dubliner Jack Kennedy, who races for the the Northern Ireland-based Mar-Train Yamaha outfit, tops the Supersport standings after a victory and second place.
Castlerock racer Marty Nutt was sixth and ninth in the Ducati 848 Challenge events.
Josh Brookes won both Superbike races, but only after twice being led by Laverty in the second outing.