SYDNEY Swans half-forward Gary Rohan will miss at least eight weeks as he recovers from a persistent hamstring injury.

The Swans have placed Rohan on the long-term injury list, citing a need to build his fitness base after the injury forced him to miss a significant amount of pre-season training.

Rohan cut a lone figure at training on Wednesday, running laps while the main group was put through its paces ahead of Friday night's NAB Challenge clash with Greater Western Sydney.

Swans general manager of football Tom Harley said Rohan hoped to be fit in time to resume playing in round six, when the Swans face the Brisbane Lions at the SCG on May 1, although he is likely to return through the NEAFL.

"Gary has been battling a hamstring problem for a number of weeks and has missed a critical portion of his pre-season preparation," he said.

"As a result, he will need at least another eight weeks preparation before he can resume playing, so for now he will continue his rehab.

"We're confident Gary will have an impact when he returns and will play out the year."

A highly rated junior thanks to his blistering speed and athleticism, Rohan was taken at pick No.6 in the 2009 NAB AFL Draft, but has managed just 61 games in his injury-plagued six seasons.

A badly broken leg suffered in round four, 2012 cost Rohan more than a year of footy and he didn't see any senior action until round 21 the following season.

At his hard-running best, Rohan is a vital member of the Swans' line-up; with his tackling pressure a highlight inside forward 50, especially over the past two seasons when he's managed to play 34 games.

Defenders Harry Marsh – who was de-listed at the end of last season and re-drafted by the Swans – and Nic Newman, plus small forward Tom Papley could be in line to replace Rohan on the senior list.