CARLTON'S worst fears have been realised, with confirmation defender Ciaran Byrne ruptured the anterior cruciate ligament in his right knee against Collingwood on Saturday night.

The 21-year-old was bumped by Magpie Travis Varcoe after a clearing kick from defence in the last quarter, which forced the Irishman to land awkwardly on his right leg.

Byrne punched the ground in frustration after the incident and was visibly upset as he was taken off the ground on a mobile stretcher.

Blues football manager Andrew McKay confirmed Byrne would now be sidelined for the next 12 months.

"Long-term injuries are always disappointing, particularly as Ciaran was having a really solid season so far," McKay told the club's website on Sunday evening.

"He will undergo surgery in the coming weeks and will commence his rehabilitation process not long after that. 

"Ciaran is a resilient young man and will have the club's full support throughout this process."

Byrne played 11 games for the Blues this season and had quickly become a key member of their back six under first-year coach Brendon Bolton.

The County Louth product first joined Carlton in August 2013 as a category B rookie, before being upgraded onto the senior list.

Byrne managed just one game for the Blues last year due to persistent hamstring setbacks.