CDK strung back-to-back wins together to firm as a favourite to make the Dunedin club twenty20 final on January 17.
Carisbrook-Dunedin and Kaikorai (45.5 points) merged their top teams this season and the premier grade team leads the T20 standings after eight rounds.
Seamer Jeremy Smith took five for 22 to help bowl out Green Island for 127 in the early game.
Former Volts all-rounder Christi Viljoen top-scored for the Swamp Rats with 51 from 36 deliveries.
But Otago batsman Josh Finnie got back into some good form. He swatted 64 from 29 deliveries and Fergus Ellis made 52 not out to help CDK record a comfortable eight-wicket win with more than six overs remaining.
Camden Hawkins led the way in the late match against rival Albion. He plundered an undefeated 104 from 59 balls as his side posted 178 for six.
The Eagles, second in the standings with 40 points, were restricted to 162 for six.
Max O’Dowd top-scored with 69 but Smith snapped up three for 40 to complete a good day of cricket.
Albion beat Taieri by 14 runs earlier in the day. It put on a total of 120 for six.
Left-arm spinner Ben Lockrose shone for Taieri with three for 18.
But Albion was disciplined with the ball and restricted its opponent to 106 for six.
North East Valley (33 points) won both its matches to stay in touch with the competition leader.
It scraped its way to 141 for eight against University-Grange. Nine batsmen scored between 10 and 19 but no-one was able to push on.
Muhammad Jawad claimed three for 19 and Jacob Cumming took a brace.
But Uni-Grange slumped to 105 all out and is yet to register a win in the tournament.
Kyle Hastie and Hunter Kindley picked up three wickets apiece for North East Valley, which had a much tighter game with Taieri later in the day.
Taieri (31 points) reached 118 for six but Valley overhauled the target with fours wickets to spare in the last over.
Green Island (27.5 points) bounced back from its earlier loss to CDK with a comprehensive 57-run win against University-Grange (12 points).
It scored 130 for eight and dismissed Uni-Grange for a paltry 73.
Keegan Russell starred with three for 14.
