Two successive wins have seen them wrap up a semi-final spot after a hard-fought 26-8 win over Port Kembla Blacks on a wet and windy Kiama Showground on Sunday.

With the last round bye and a far better points differential than Jamberoo, with whom they share fifth spot, the win over the Blacks came at the best time.

In a huge upset, Gerringong Lions will now have to defend their premiership from the unaccustomed position of fourth spot, after they lost an old-fashioned, wet-weather slug fest against Albion Park-Oak Flats 14-6 at Centenary Field.

In other weekend games, competition leaders Warilla-Lake South Gorillas and Jamberoo Superoos battled out an at-times spiteful game in fine conditions on Saturday, with the Gorillas delivering what turned out to be a fatal blow to the visitors' semi-final hopes with a 30-14 win.

Nowra-Bomaderry Jets wrapped up third spot with a 36-14 win over Berry Magpies, while Shellharbour City Sharks kept their roll going with a 64-0 win over a depleted Milton-Ulladulla Bulldogs at Ron Costello Oval.

In the game at Kiama Showground the Knights jumped to an early 8-0 lead in the first 10 minutes via two Jacob Dolan tries, before the Port Kembla side lifted and closed the gap to 8-4 at half-time, despite running into the southerly.

With the wind at their backs and tactical kicking of coach Mark Simon, it was expected the Blacks could win, but they failed to capitalise on the advantage with a series of handling errors and the strong Knights defence prevailed.

In the end the Knights were able to come home with three second-half tries to Corey Grigg, Jacob Morrison and Matt Emerson, with the Blacks' sole reply coming from hooker James Weir.