Sydney star Lance Franklin could miss more than half of the AFL season after sustaining a serious hamstring injury.
Franklin hurt his hamstring doing some running drills at training on Wednesday and had a scan on Thursday.
He won't be able to resume running for 3-4 weeks.
"It's slightly worse than the (hamstring) injury he sustained last year when he missed about nine weeks, that might be an indication, but we just don't know until he get into his rehabilitation and we see how he progresses,"' Swans' general manager of football Charlie Gardiner.
"We will obviously be guided by the medical team; they are also seeking advice in relation to the best treatment and management of the injury going forward."
Gardiner said it was a new injury on Franklin's right leg.
"Probably one of the positives is that there's no tendon damage in the hamstring," Gardiner said
The 33-year-old spearhead, who is in the seventh season of a lucrative nine-year deal, played only nine games in 2019, bringing up his 300th appearance in the Swans' final fixture of the season.
His wife Jesinta said she had seen some nasty comments online about Franklin and stressed the mental toll that injuries took on players.
"When they hurt themselves or they injure themselves, it's actually mentally extremely challenging,'" she told Channel Seven.
""I think people just need to be really understanding of that.
"He is really tough, he has been playing for 17 years now."