Just when it seemed the Illawarra Rugby Union premiership was a two-horse race, defending champions Shamrocks served up a timely reminder they are anything but a spent force.

The Woonona-based side can't finish any higher or lower than third, but Saturday's 22-15 road win over equal-leaders Shoalhaven showed they have no intention of handing over their crown.

"It was a pivotal game for us, a really defining game, and to come away with the result we got was really satisfying," said Shamrocks coach Brendan Schoupp.

"It's okay for people to think we're not where we were last year, but that game showed we can beat anyone above us.

"The will to win was fantastic and the boys showed their character. They showed they're ready and how much they want it. They answered the challenge and any other questions I might've still had about us."

Scoring tries for the Rocks were Peter Rowling, Raihania Whaanga and Cameron Thompson (2), while Scott Terasenko booted one conversion.

Shoalhaven got their points through tries to Chad Frazer and David Sproule, with Leith Cooper kicking a conversion and penalty goal.

Shoalhaven secured a bonus point to grab a share of first spot with Avondale.

"One of the more pleasing aspects of the win was that the things we've been working on all year are starting to pay off," Schoupp said.

"We changed things structurally and it's a credit to the players how they've adjusted and persevered.

"Shoalhaven are a very good team and they're very well coached, so to beat them down there will only boost our confidence.

"We finish the season against Uni and it's probably even more important that we carry the same form into that game and go into the semis on a really positive note."

Meanwhile, Bowral are perfectly placed to claim fifth spot after beating Tech Waratahs 20-13 at Saunders Oval.

The Blacks are outright fifth after the win, while Tech Waratahs dropped to sixth.

The Tahs will only reach the finals if they beat Avondale in this weekend's final round and Bowral lose at home to Shoalhaven.

Vikings dealt University's top three hopes a big blow with a 14-13 triumph at Vikings Field, while Kiama thrashed Camden 48-7 at Kiama Showground.

Table: Shoalhaven 63, Avondale 63, Shamrocks 46, Uni 41, Bowral 38, Tech Waratahs 34, Vikings 29, Kiama 24, Camden 7.