Geelong has confirmed that promising young defender Jackson Thurlow will miss the entire season after tearing his ACL in his right knee.

The 20-year-old underwent scans on Monday, after he was stretched off the ground following a collision with Essendon's Mitch Brown during Saturday afternoon's NAB Challenge match in Shepparton, and will undergo a full knee reconstruction.

“Confirmation that Jackson has torn his ACL is extremely disappointing for him and the club,” Geelong General Manager of Football, Steve Hocking said.

“His development came along in leaps and bounds last year and he was definitely in the mix to become a permanent member of our back six this season after showing great promise throughout the pre-season.

“As a club we will ensure he is provided with all the support he needs to work through the process.”

Thurlow, who was selected with pick No.16 in the 2012 National Draft, enjoyed a breakout year in 2015, playing 19 senior games for the Cats.