The finals are just three weeks away and Wollongong are flexing their muscles despite eight players backing up from reserve grade in a torrid 15.12 (102) to 13.8 (86) victory over Bomaderry at Keira Oval.

Despite a third of their best 22 unavailable on the final weekend of the university semester break, Wollongong still posted their second win this season over the Tigers, who slipped from third to fourth.

"We thought we'd have a few more back this game but it didn't work out that way but the guys who came in were outstanding," Bulldogs coach Lee Murray said.

Wollongong edged ahead of Kiama on percentage with the minor premiership likely to be decided when the powerhouse clubs meet at Bonaira Oval in the final round on August 16.

"There's bigger things to win than the minor premiership so it's not a big deal, but playing Kiama will be big just before the finals," Murray said.

Nick Davidson played all eight quarters through the two grades against Bomaderry and booted two key goals in first grade.

Dogs ruckman Cameron Bailey, Tom Potter and midfielder Aaron Guy also led the way in a bruising clash, in which the biggest margin was Wollongong's 18-point lead at quarter-time.

Bomaderry won the second and final quarters and remain a premiership contender.

Meanwhile, Northern Districts took another step towards a finals double chance with a 15.7 (97) to 7.10 (52) win over Figtree at Hollymount Park.

Norths leapfrogged Bomaderry into third spot and face the Tigers on Saturday.

Norths are also just a win behind co-leaders Wollongong and Kiama with three rounds left.

Adam Carmody (seven goals) and Jared Wilson (five) provided clinical finishing for the Tigers against Figtree, who trailed by only 15 points at three-quarter time.

Shellharbour Suns are having their best season in first grade after their 148-point thrashing of Port Kembla became the club's seventh victory of the season.

In a big day at Jock Brown Oval, it was the first time in the Suns' five-year history their first and reserve grade teams had won on the same day.

Brock Ashton booted eight goals with Elwyn Roberts and Brendan White four goals each.

"It's a massive achievement for the club and reward for a lot of hard work," Suns president Marcus Hollingsworth said.

There was also cause for celebration for Nowra, who outclassed Albatross 15.19 (109) to 2.5 (17) at Tom Smith Oval.

Taigen Dubbelde booted four goals to lead the Blues to their third win of the season.