After two days of pool matches, the pressure ramped up - along with the temperature - at Jubilee Park on Sunday as the Southern Conference carnival entered sudden death finals.

There was no room for slip-ups, and no hint of them from the Vipers' most impressive young talent as the Under 10 and Under 12 girls stretched their unbeaten streaks through a third full day to claim memorable JSC championships.

The U10 girls hadn't conceded a try in the eight straight wins that took them to the decider, where they put the crucial first one on the board against Balmain amid a raucous carnival atmosphere with grand finals all on next to each other.

New scoring to avoid draws and overtime means the first try in a sudden-death game is worth 3 points, and every other try is worth two points.

Balmain twice responded to Wagga and trailed 5-4 but the Vipers defence then held and their star Isabel Baggio put the game away with her ability to spot an opening, as she crossed for all four tries and a 9-4 scoreline.

"I'm so, so proud. They're just absolute champions. So much talent, so much speed... they're unbelievable," coach Virginia Baggio said.

"They are a beautiful bunch of girls who work hard for each other, they've trained hard since November, they're willing to listen and learn, and they're so fun to be around. That positive attitude makes a difference."

It was rewarding for the coach who steered Wagga's U10 girls to a runners-up finish two years ago.

And it was redemption for those players too who, on an outside field and coached by Baggio's husband Andrew, the U12 girls claimed a second Wagga title at the same time.

The U12 girls scored the first two against Cronulla and held on for a 7-2 victory. It closed their tournament with the amazing record of 51 tries in nine games, while conceding just seven as Abbey Hunt, Paige Plum and Halle Baggio led a superb team effort.

"The girls just had a never-say-die attitude. They kept on running. We had an injury and they just kept on pushing. They're only 11 years old but they're so tough," Andrew Baggio said.

"Everything steps it up in the grand final - there's screaming and yelling and there's so much going on. There's a lot to process but they stood up, they ripped in and they've played some really good touch."

Only Hills Hornets, with three premiers, out-performed the Vipers as an association. The Sydney club claimed the U14 double as well as the U16 girls grand final.

Their U14 girls beat Balmain 16-15 in a thriller, fighting back after conceding the first try, and trumping Balmain on the final siren. Their U14 boys beat Penrith 13-6 and the U16 girls won 11-2, also against Penrith, who had a rough day after qualifying four teams for grand finals.

The Vipers were the only other club to win multiple titles and had hoped to match Hills' three wins when they took on Orange in an all-country U18 girls grand final.

Wagga had beaten their arch-rivals by one try in the pool game then both teams powered past Sydney opponents in the quarters and semi-finals to set up a rematch.

But Orange got Wagga on the back foot with an early try, showed intensity in defence and had the game in the bag just after half-time, on the way to six tries and a 13-4 win.

Wagga's crossed through wingers Claudia Wheatley and Leila Wadley who were superb through the carnival.

"They're a real point of difference between us and some of the other teams... they're quick, they get involved, and we've got some girls who can throw a good long ball to get them in space," coach Evan Robertson said.

He was thrilled with his team's efforts across the carnival but complemented the well-drilled Orange outfit for bringing their A-game when it mattered.

"They've been together a long time. But we play each other a lot, both teams know how each other works. So it's a matter of whoever does what they do best, on the day. And they got us today."

Orange coach Glenn Prestwidge was surprised by the margin against their toughest opponents and praised his players, with the team led throughout by Josie Clark and Hayley Prestwidge.

"It's a good effort. We've had a lot of injuries and they just hung in there. And their defence won it for us," Prestwidge said.

The tournament closed with an U18 boys clash of the titans and Parramatta and Penrith didn't disappoint.

The Eels got the critical first try but it was a seesawing affair and twice the Panthers came from three points down. And with less than a minute left, they looked to have caused an upset with a long ball to the left wing and seemingly the matchwinning try.

But Parramatta charged down field in the last 30 seconds and Finn Watkins scooted from dummy half and found winger Dylan Bissett who declared he's never scored a winner to match it.

"Nothing like this, no. I just put the ball down, in an acre of space. It means a lot. It's an amazing feeling," he said of their first JSC championship, having played with the Parramatta team right through.

Parramatta coach Josh Phillips has taken them along for the ride and saw them out of juniors on the happiest of notes, with an undefeated carnival.

"It's a huge effort for them. I've had these boys since they were 10 years old so to win with 12 players, it's a big effort," Phillips said, admitting he'd almost given up at the finish.

"It was pretty tight. And the last call was pretty tight but we'll take it. They're a quality side Penrith, and they only had 11 players all tournament, so that was a big job."

Penrith, Cronulla and Wests also went home with one title each.

Penrith beat Wollongong 5-0 in the U10 boys grand final.

Cronulla beat Balmain 13-4 in the U12 boys.

Wests beat Cronulla 7-2 in the U16 boys.

MORE PHOTOS from Friday's opening day: Flying starts set Vipers up to strike | Photos

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