Carlton defender Sam Docherty ruptured his ACL at training on Wednesday morning and will miss 2018.
His leg is understood to have buckled under him as he undertook a regulation non-contact running drill.
The 24-year-old won the Blues’ 2016 best and fairest and was runner-up in 2017 as he emerged as one of the game’s best defenders since crossing from the Brisbane Lions to Carlton in 2014.
Docherty was named All-Australian in 2017, the first Carlton player since 2011 to be awarded that honour.
He will undergo traditional surgery in the coming days and the Blues have ruled him out from returning until 2019.
Carlton football manager Andrew McKay said the club was disappointed for Docherty but he expected other players to take the opportunity presented in his absence.
“Sam is a total professional and a resilient young man and we know he will face his rehabilitation process with the utmost dedication,” McKay said.
“As a terrific young leader at our club, Sam will continue to work with the leadership group and assist in the development of our young players both on and off the field.”
The Blues traded out Bryce Gibbs to Adelaide in the recent trade period meaning they will be without two of their top four placegetters in the 2017 best and fairest during 2018 as they look to improve under Brendon Bolton.