South Coast Thunder held Manly-Warringah to just one goal after half-time and stormed home for a 25-point victory in Saturday's Sydney AFL Division One under-19s clash at North Dalton Park.

The Thunder are in their first season in the elite Sydney AFL and claimed back-to-back wins for the first time with an impressive 9.11 (65) to 5.10 (40) victory over the Giants.

The Thunder were coming off beating Sydney Uni in their first away win and overcame a 13-point half-time deficit against the higher-placed Manly to boot seven goals to one in the second half.

"The confidence in the group is high and now we're focusing quarter by quarter, 20 minutes at a time rather than the whole game the team is playing well," Thunder coach Dave Forst said.

"We're a young group with talent and it's just a matter of maturity and sticking to the game plan and the rest will look after itself.

"We might have kicked a few more goals but seven goals to one in the second half is really pleasing and shows that we are moving in the right direction."

South Coast had 10 goal-kickers with Jaad Matesic booting two, while ruckman Luke Essenstam, midfielder Jaiden Browne and defender Jack Thompson-Gardner were outstanding.

Manly were the better team in the first quarter, with six scoring shots to just two Thunder behinds for a 14-point lead.

Both teams booted two second-quarter goals, with the visitors leading by 13 points at half-time.

South Coast took charge in the third quarter, booting three goals and keeping Manly to only three behinds.

The home side went on with the job with a four-goals-to-one final term for a deserved win.

The Thunder were formed by AFL South Coast to replace the Wollongong Lions in Sydney AFL and, with three wins from their first nine games, are making a fine impression.

The Thunder have one of the youngest lists in the premier under-19s competition, but are handling the step up in standard.

This Saturday the Thunder face their toughest test, away to unbeaten leaders Pennant Hills.