He doesn't turn 21 until Wednesday but Manly star Kieran Foran has come of age, demonstrating an ability to spearhead the Sea Eagles' NRL premiership campaign.

Manly were on the back foot and in serious trouble against South Sydney at Brookvale Oval on Sunday until the dynamic five-eighth flicked the switch and inspired a 36-22 victory.

The Sea Eagles trailed 16-22 heading into the final half hour, but Foran ensured his side maintained second place on the ladder with back-to-back individual tries, laced with his trademark class and tenacity, in front of 19,856 fans.

Foran shapes as Johnathan Thurston's main rival for the Dally M Medal and, with the North Queensland halfback most likely out for the majority of the regular season, his Kiwi rival has a golden opportunity to close the gap.

Even a recent decision to cut his long hair was motivated by on-field performance and Foran revealed he wanted to stand up and lead the Sea Eagles to glory.

"I've tried to do that this year, I wanted to put that responsibility upon my shoulders a bit more this year," said Foran, who got rid of the locks when they started to obstruct his vision.

"I've played enough games now to be able to make a difference within the team ... and lead from the front ... and that's something I've wanted to do this season. I'm just going to keep working on it and hopefully keep getting better and better."

Manly captain Jamie Lyon said Foran plays like a "veteran" despite his youth and, while coach Des Hasler wasn't particularly impressed by his team, who looked complacent when coming back from halftime up 16-8, he praised Foran for his special touch.

"He's been doing that all year. To come up with two tries was what we needed at the time," said Hasler.

"You need those big plays from those players."

South Sydney's own big-player quartet of Chris Sandow, John Sutton, Greg Inglis and Nathan Merritt combined well to get the Rabbitohs on the way to an important upset win.

However, lapses in concentration and poor goal-line defence, particularly by their right-edge, meant meek surrender to the fast-finishing Sea Eagles.

Coach John Lang was left disappointed, with Souths missing a golden opportunity to get amongst the teams level at the back end of the top eight.

"We got to that lead by playing really good solid footy (and then) we gave them opportunities down our end and they took it," said Lang, who has Ben Lowe on report for striking Brett Stewart.

"It's frustrating we did all that good work and then wasted it."

David Williams scored twice for Manly, while Michael Robertson and Michael Oldfield also crossed, while Stewart of course nabbed his customary try at Brookvale.

Hasler is pleased with where his side sit at the end of the representative season - one win back from 1st placed Melbourne.

"As long as you are winning games (at this time of the year) then that's okay," he said.

"We just need to pick up right across the board now and we will."

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