Oak Flats are on course to defend their South Coast one-day crown after booking a spot in the final with a comfortable win over Shellharbour at Geoff Shaw Oval.

Oak Flats won by five wickets after restricting Shellharbour to 8-165.

Nick Formosa (58) and Ben Mitchell (47) top-scored for Shellharbour, while Steve Maloney (2-8) and Ben Morrow (2-10) led the way for Oak Flats with the ball.

Kieran Gray (55) top-scored for Oak Flats (5-170), while Andrew Newman (33 not out) and Zac Hilton (34no) put on an unbroken 74 for the sixth wicket, with the Rats winning with more than 15 overs to spare.

The victory ensured Oak Flats of a spot in the December 21 one-day final, with one more limited overs round remaining.

"We had a pretty understrength side against Shellharbour but it just shows the depth we have," said Oak Flats skipper Ryan Chatterton, who missed the match with a back injury.

Meanwhile, Lake Illawarra and Kookas will meet on Saturday to decide the other one-day finalist after both had big wins in round eight.

The Lakers (3-194) beat Gerringong-Jamberoo (9-192) by seven wickets at Howard Fowles Oval, with Greg Connor making 74 and taking 2-24. Nathan Tyrrell also made an unbeaten 44, while Lakers skipper Shane Cody took 2-32.

Dan Jones (47) and Matt George (44) led the way for Gerringong.

Kookas skipper Gerard Healey (41) top-scored in a low-scoring 72-run win over Kiama.

Twenty wickets fell for just 200 runs as Kookas recovered from 5-32 to make 136.

Eric Davies took 5-7 off just 7.4 overs in an excellent spell for Kiama but was undone by his batsmen, with the Cavaliers bowled out for 64.

Josh Cuthbert took 3-18 and Scott Cox 3-13 for Kookas.

Andrew Warren starred with an unbeaten 97 and 3-29 for The Rail, who scored 6-200 but finished 12 short against Albion Park (6-212).