The Matthews Cup Sharks continue their push towards a finals berth, while their SG Ball colleagues stayed in touch with a crucial victory, as the two junior Sharks sides scored wins over the Roosters at PointsBet Stadium.
The Matthews Cup Sharks were always well in control before cruising to a 42-10 win, while in the SG Ball, in heavy rain the Ball Sharks handled the conditions best in beating the second-placed Roosters 12-4.
The win and the heavy points differential will see the under-16 Cronulla side in a strong position with three rounds remaining, while the Ball Sharks kept their hopes alive with the gutsy victory.
In the Matthews Cup clash a line break from backorder Hayden Westwood resulted in a Kobi Douglas try, the first of three the Sharks centre would score on the day, and when Siteni Taukomo converted it was 6-0 to the home side.
Some soft goal line defence from the Roosters saw Cruiz Devine crash over for the Sharks second and when Douglas left above the pack to pull in a Max Demeio cross-field kick to score soon after, with two successful conversions it was 18-0 to Cronulla.
The Roosters would bridge the gap with a converted try after repeat sets on the Sharks line however two further touchdowns, the first to hooker Taj Brailey and a third try for the half to Douglas on the stroke of half time saw the teams go to the break with the scoreline at 28-6.
With conditions worsening as rain began to fall at PointsBet Stadium the second half was a scrappy one, Sharks notching three tries, to winger Joel Patton, centre Tyrell Fakaua and a second to Devine in completing the scoring. The Roosters crossed for a consolation try as the full time siren was sounding.
The SG Ball match followed with the rain making flashy football next to impossible as the match turned into a grinding affair.
The Roosters went over first, before Kade Dykes would level the scores with a Sharks try in the 15th minute.
The Sharks put their noses in front when winger Harley Lester went over and it was the Cronulla under-18s up by 8-4 at half time.
With handling difficult nether team was able to mount any real pressure in the second period but it was the Sharks who were hanging tough against their highly-rated rivals, a penalty goal to half back Cody Fuz extending their lead to six points.
The Sharks would hang on, Fuz pushing the lead out to a match-clinching eight points as the Cronulla side would claim an extremely valuable two points.
Coach Chris O'Connell was extremely pleased with the defensive effort and the grit displayed by his team in the testing conditions.
The SG Ball Sharks team are in action next week against the Victorian Thunderbolts, while the SG Ball boys have a bye.
Kobi Douglas 3, Cruiz Devine 2, Joel Patton, Tyrell Fakaua, Taj Brailey tries, Siteni Taukomo 5 goals
Kade Dykes, Harley Lester tries, Cody Fuz 2 goals