Northern Ireland riders Keith Farmer and Andy Reid secured victories at round two of the British championship at Oulton Park on Monday.
Farmer was a convincing victor in the Superstock 1000cc race and lies second in the series behind Taylor Mackenzie.
Reid is 16 points ahead of his nearest challenger in the Supersport standings after triumphing in the feature event.
Michael Laverty is third in the British Superbike series after taking sixth and fifth finishes for the Tyco BMW team.
Laverty's team-mate in the Moneymore-based outfit, Christian Iddon, was runner-up in both races at the traditional May Day meeting, but heads the championship by 14 points.
Former British and European Supermoto champion Iddon boasts 72 points, with Shane Byrne on 58 and Laverty on 56.
Seeley crashes out unhurt in race two
Alastair Seeley achieved a fine fifth place for the RAF Reserves BMW outfit in Monday's opening race, but crashed out unhurt in the early stages of the second race.
Glenn Irwin was 13th in the opener on his Ducati, but made his way through the field in the next outing to end up in seventh spot.
The races were won by JG Speedfit Kawasaki rider Leon Haslam and Buildbase BMW pilot Richard Cooper, his first-ever success in a BSB race.
Jordanstown man Reid emerged the winner of Monday's Supersport race, having had to settle for seventh in the sprint outing on Sunday, in which Andrew Irwin was fourth.
"I knew I had to push hard to get into the lead as I know I have a good pace round here when I get in front," said Reid after taking the chequered flag.
Farmer is 10 points adrift of Scot Mackenzie in the the Superstock 1000cc class, with Josh Elliott fourth overall after his fifth-placed finish.
Carl Phillips took fourth in the National Superstock 600cc race, with Aaron Wright continuing his winning run by coming home first in the KTM Junior Cup events, in which Scott Swann was 11th and sixth.