Persistent Sydney youngster Kristin Thornton will finally make his AFL debut on Saturday against Carlton, after being one of three footballing brothers to overcome a serious knee injury.

The 21-year-old utility was on Sydney's senior list from 2006 to 2008, but was delisted last year after missing the season because of a knee reconstruction.

The Swans then gave him a second chance on their rookie list before he was promoted to the senior roster earlier this season and he will finally make his AFL debut on Saturday.

"This has been a long time coming and I've finally got my opportunity," Thornton said on Friday.

Thornton and teammate Nick Malceski suffered anterior cruciate ligament damage within a week of each other last year.

While Malceski was back playing in the senior side again by round eight after undergoing radical surgery, Thornton said he declined the offer to do likewise.

His family know all about knee injuries.

"My twin brother Bryce did his knee this year and my older brother did it the year before I did it," Thornton said.

He admitted last year the thought entered his head that he might never play a senior game after getting injured and spending three frustrating years waiting for an opportunity.

"I did find it frustrating, but I guess the longer the wait the sweeter it is at the end, so I'm happy now I've finally got there," Thornton said.

His parents and Bryce, who have supported Carlton in the past, will travel to Sydney to watch his debut.

Thornton's inclusion at the expense of the injured Jared Crouch is the only change to the Sydney side, while Carlton has recalled running defender Dennis Armfield in place of rookie Jeff Garlett.

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