SYDNEY SWANS academy recruit Lloyd Perris has undergone another round of surgery on his troublesome left knee and will be sidelined for 10 weeks after a training mishap last week.

Perris, who spent three years in the Swans' Academy before earning a spot on the rookie list at the end of 2013, damaged meniscus cartilage on the knee he had LARS Surgery on halfway through last year.  

While the Swans have a relatively healthy list heading into the NAB Challenge, the club has also been forced to hold back prized youngster Isaac Heeney with knee tendinitis.

While Heeney has been able to build his workload in recent weeks and could play pre-season games, Perris will likely be unavailable until early May.   

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"Lloyd hurt his knee slightly before Christmas and thought it was OK, but he tweaked it a little bit last week," coach John Longmire told 

"He went and had it operated on today and it was a successful operation.

"It was repaired, which was a good thing, but it will be about 10 weeks [on the sidelines]."

Perris had only resumed full training this week after a long period of rehabilitation, and the setback will delay his ambitions of pushing for a senior debut this year.

Longmire, however, said the 20-year-old was well equipped to rebound from the disappointment. 

"He's clearly disappointed that he's had to go and have another operation, but he's a pretty resilient kid," the coach said.  

"He's determined and he attacks his rehab with enormous vigour and effort, and he knows he gives it his best.

"He knows what's in front of him and I'm sure he'll do a good job when he gets himself back.

"Having it done now means he's still got the majority of the season to perform."

Heeney, who was recruited as a 'steal' from the Swans' academy with pick No.18 in the 2014 NAB AFL Draft, has been monitored closely this summer because of knee tendinitis.

The complaint kept him out of last year's draft combine, but Longmire was confident the 18-year-old would be able to show his ability after gradually increasing his program over the pre-season.

"He's been building up to the point now where he's playing games, and he's doing really well," Longmire said.  

"There's been a fair bit talked about him I guess, and he's certainly been used to push different arguments over the journey. 

"But he's just one of our 44 players now, and we've got to make sure we develop him as we do others.

"I do like what I've seen so far, but it's only early days."

Isaac Heeney is a $246,000 midfielder in NAB AFL Fantasy this year. Create and fill your AFL Fantasy Classic league by March 2 to win a free AFL Live pass.