Sydney star Lance Franklin could miss at least half of the AFL season after sustaining a serious hamstring injury.

Franklin injured his right hamstring at a Swans training session on Wednesday and had a scan today.

Swans general manager of football Charlie Gardiner said the club was unsure when Franklin would be fit again to play this season, as he would not be able to run for three to four weeks.

Gardiner said it was possible Franklin could be ruled out for a longer period than he was last year when he was sidelined with a left hamstring injury.

“I think it’s slightly worse than the injury he sustained last year when he missed about nine weeks,'” he said.

“That might be an indication, but we just don’t know until he gets into his rehabilitation.”

Gardiner described the injury as “decent”, but said it was fortunate Franklin had avoided tendon damage.

The club is now in the process of planning an appropriate rehabilitation program for Franklin.

“We will obviously be guided by the medical team,” Gardiner said.

“They are also seeking advice in relation to the best treatment and management of the injury going forward.”

The 33-year-old Franklin is in the seventh season of a lucrative nine-year deal.

He played only nine matches in 2019, bringing up his 300th appearance in the Swans’ final fixture of the season.

The Swans restart their 2020 season on June 14 when they host Essendon at the SCG.

AAP/ABC