ERROL Gulden continued his All-Australian calibre season on Saturday night with a best-on-ground Sydney Derby outing, and his coach John Longmire says the left footer's form is no fluke.

Gulden racked up 32 disposals in the wet conditions at Giants Stadium and kicked two stunning goals to win his first Brett Kirk Medal and be the driver of Sydney's 11-point win.

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The 21-year-old is in his third season and is averaging 26 disposals to go with 18 goals.

When asked about Gulden's impact, Longmire could only smile.

"He's not a bad young fella, Errol, he goes alright," Longmire said with a slight chuckle.

"He's just got a great mix, always has. He works really hard at his game.

"He watches opposition vision, he's all over stuff, he contributes in meetings, always has, he trains as hard as any player and he runs hard and works hard on game day.

"They're the things he does, and he's got a bit of talent as well, but he doesn't rely upon that. He works super hard."

Gulden's first goal was a miraculous 40m checkside on the run from the left boundary line, while his second came during the tense fourth quarter via a 48m snap off two steps.

He also had a game-high 677m gained and an equal game-high eight score involvements.

Gulden was just one man to impress for the victors, who kicked 11 goals from 23 inside 50s without a miss in the first half on the way to victory.

Hayden McLean kicked four goals in the first game following Lance Franklin's retirement, while veterans Jake Lloyd, Luke Parker and Callum Mills were also influential.

Longmire was delighted with the performance to snap GWS's seven-game winning streak.

"We were efficient in front of the ball, which really helped in the first half," he said.

"Some of those stats you don't see every day of the week, but you take them when it comes.

"The first half we tried to not let them get settled too much because once they get settled, they're very hard to break through.

"So we just tried to disorganise them a little bit."

Opposing coach Adam Kingsley said his team was taught a lesson, but was confident it could rebound over the remaining three weeks of the home and away season.

The Giants had 40 inside 50s to the Swans' 23 at half-time, yet trailed by 18 points.

The most staggering statistic though was that 10 of Sydney's 11 first-half goals came via chains that started at their defensive end, a fact Kingsley called "extraordinary".

"We just didn't, and were unable, to stop their ball use from the back half," he said.

"We didn't defend. We had plenty of opportunities to score ourselves, but they defended our entries really well.

"We got a lesson on if you don't finish your work you get punished and if you don't defend the opposition in your front half you can get punished too. That was really the game.

"I thought their work-rate forward was really strong. 

"It wasn't rocket science, but they were doing it extremely well and we weren't defending it, obviously.

"We've got some work to do on that and try and improve. Typically we've been pretty good in that space, but we weren't tonight."

Finn Callaghan was a late withdrawal – after the warm-up – with calf soreness and will be assessed during the week.