SYDNEY Swans coach John Longmire has expressed his dismay for young forward Gary Rohan, who will miss the rest of the season after breaking his leg just two minutes into Sunday's 36-point victory over North Melbourne.

Rohan kicked the game's first goal in the opening minute at the SCG before falling awkwardly in a tackle inside the 50m arc just 60 seconds later, with the club later revealing he had suffered a compound break of the tibia bone.

Limited to 18 games across 2010 and 2011 due to injury, the sixth pick in the 2009 NAB AFL Draft was showing some of the enormous potential he possesses this year and was a key to the club's unbeaten start.

His loss a huge blow to the Swans' set-up.

"He's got a terrible broken leg and is out for the year," Longmire said after the Swans' win that took them to 4-0 for the season.

"It's a real shame for him. He's such an exciting talent and a terrific kid to have around the footy club.

"I'm sure the players will get around him and help him through it and his family is up here (from Cobden in western Victoria), which is good.

"But it's obviously a blow for us."

Considering how early Rohan's injury occurred, and with Adam Goodes (suspension) and Shane Mumford (back) already absent, Longmire was pleased with how his troops held the fast-finishing Kangaroos at bay.

Trailing by 40 points at three-quarter time, North Melbourne rallied before the Swans steadied and will now head into next week's clash with Hawthorn as one of only three unbeaten teams - alongside West Coast and Essendon.

"We're really pleased to play quality opposition like North Melbourne, who we thought were in terrific form," Longmire said.

"We were missing a few players, but the important thing for us was the players that came in really contributed as well.

"That's what we're after and that's what we got, which was pleasing."

James Dampney covers Sydney AFL news for AFL.com.au. Follow him on Twitter: @AFL_JD

The views in this article are those of the author and not necessarily of the AFL or the clubs