Rockingham Sharks dented the WA Rugby League premiership hopes of Joondalup Giants with a 34-30 win on Saturday.
The Giants needed a win to keep themselves in touch with the leaders and a top four spot.
They were able to put on some good hits but the efforts of John Taithua and Vincent Silulu got the home side over the line.
Gus Marshall was best for the Giants with two tries while Nathan Chaplin excelled at hooker.
Fremantle cantered to a 38-18 victory over Willagee at Webber Reserve, a victory that furthered their finals aspirations.
The Roosters toyed with the Bears in the opening exchanges and took an 18-8 lead into the break.
North Beach Sea Eagles scraped home 14-10 against Kalamunda Bulldogs at Pioneer Park to put South Perth's minor premiership celebrations on ice.
The win also gave them a three point gap on Willagee and Fremantle as the competition heads towards the finals.
1. South Perth 31
2. North Beach 23
3. Willagee 20
4. Fremantle 20
5. Joondalup 16
6. Rockingham 14