YOUNG forward Josh Mellington was the 'bolter' of Fremantle's pre-season, rising above the pack of fringe players and forcing his way into a full-strength team ahead of round one.

He held his own as a small forward in the early rounds, too, booting three goals against reigning premier Geelong in round one and adding value with his defensive pressure.

But against the Brisbane Lions in round three, the 19-year-old suffered a serious hamstring tear - similar to that suffered by St Kilda captain Nick Riewoldt in 2010 - and his pre-season gains were undone.

"I got the ball centre-wing and just turned really sharp to sprint and I felt something like a really bad spasm or cramp in my hamstring," Mellington told AFL.com.au this week. 

"I tried to keep running and as soon as I went to kick the ball it just felt like someone had slashed the back of my leg with a knife. I knew something had gone pretty wrong."

Mellington had surgery in Melbourne three days after the injury and expects to be sidelined for 10 to 12 weeks, with his rehabilitation program to take shape when he returns to consult with his surgeon in three weeks.   

The second-year forward started running last week and is moving at 80 per cent capacity, with a focus on slowly recovering the fitness base he had built over the summer.

"Speaking to the strength and conditioning coaches and the medical staff at the club, they're not going to rush me to get back for one or two extra games," he said.

"I don't want this injury to ever occur again and you need to prevent everything else that comes along with having a soft tissue injury.

"I want to come back physically primed and ready to go at the end of the year.

"Physically I'm in pretty good shape, it's just a matter of strengthening around the hamstring to make sure it doesn't happen when I come back."

Mellington, who was recruited with pick No.56 in the 2010 NAB AFL Draft, has plenty of teammates capable of guiding him through his rehabilitation, with Anthony Morabito, Michael Barlow and Nick Suban all suffering serious injuries early in their careers.

Second-year midfielder Viv Michie, who is contracted through to the end of 2013, will also be valuable company on the sidelines as he recovers from a second serious foot injury.

"The guys at the club are very supportive and a lot of them have had those injuries so they know what you're going through," Mellington said.

"Football clubs are good at keeping you involved and occupied when you're injured and not letting the game get ahead of you.

"So when I come back I don't think my football brain's going to be fading away. It's just a matter of getting that physical side back."

Mellington said the injury hit him hard given he was playing senior football at the time, but he drew confidence from his ability to work into Fremantle's best 22 for the start of the season.

The strong-bodied teenager impressed with his stoppage work in the WAFL late last season and said he had an ambition to work into the midfield later in his career.

"I definitely see the defensive pressure as a strength of mine and Ross (Lyon) and a lot of coaches love a small forward that can apply a lot of pressure," he said.

"All smaller guys have an ambition to get in the midfield, but I'm only young and I'm trying everything I can to get a game. What position that's in doesn't really matter."

Nathan Schmook covers Fremantle news for AFL.com.au. Follow him on Twitter: @AFL_Nathan