LUCKLESS St Kilda youngster Daniel Markworth is likely to miss the rest of the season after suffering a serious hamstring injury in the VFL on Sunday. 

The 22-year-old, who is yet to play a senior game after being drafted by the Saints in the second round of the 2011 NAB AFL Draft, won't require surgery. 

However, the strain has been assessed as high grade and needs a period of between nine to 10 weeks for recovery, meaning his season is in tatters. 

"He is unlikely to return to play this season but we look forward to him being available to start pre-season training in November," Saints head of football Chris Pelchen told AFL.com.au. 

It's the second time the skilled forward has had his season cruelled by injuries after a knee reconstruction in December 2012 ruined the following year. 

While Markworth resumed playing in the VFL before the end of 2013, he didn't make it into the AFL for his debut. 

This season started off with a minor setback when he needed scar tissue cleaned out from his reconstructed knee shortly before Christmas. 

But he was playing in his ninth VFL game on the weekend, and given the Saints' season and rebuilding mode, was likely to be looked at for a senior debut this year if his form continued to track forward. 

The hamstring injury is to the same leg as his reconstructed knee but is unrelated. 

His reconstruction used the patella tendon from his opposite knee rather than a hamstring graft. 

Meanwhile, veteran Sam Fisher's latest comeback attempt has been cut down by a disc injury in his lower back, sustained on Sunday in his first VFL hit-out in nearly two months. 

Fisher ramped up his training in recent weeks following persistent pre-season back issues and an annoying hamstring problem that has kept him from senior football this year. 

But he lasted less than a half in Sandringham's 24-point loss to Williamstown before he suffered the injury when he was bending over for a contest. 

The Saints remain optimistic he could still play in the VFL this week after scans ruled out serious damage. 

But given his history with injuries this season and the fact his momentum has again been halted, he will need to pass a fitness test later in the week and is rated a 50-50 prospect to play. 

Tom Simpkin and Luke Dunstan (shoulder) are both expected to be available to face Richmond on Saturday.

Simpkin was subbed out of the Saints' loss to West Coast on Sunday after copping a knock to his shoulder in the third quarter, while Dunstan didn't play.