YOUNG Carlton star Patrick Cripps will be sidelined for up to 12 weeks after suffering a stress reaction in his lower back.

The 21-year-old experienced discomfort during Wednesday's training session and scans on Thursday revealed the injury.

Carlton's head of football Andrew McKay confirmed the bad news.

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"While the news is disappointing, the positive is we have diagnosed the condition early, minimising his time on the sidelines," McKay said.

"Given his professionalism and determination, we are confident Patrick will be ready for the 2017 pre-season competition."

After playing just three games in his first season, 2014, Cripps has played 41 of the next 44 over the past two seasons.

He won the John Nicholls Medal as Carlton's best and fairest in 2015, and backed up with a third place in last year's count, averaging 27 disposals, 17 of them contested.

Cripps' young teammate Harry McKay suffered a similar injury in March last year, before returning in late June for the Northern Blues in the VFL. 

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