Swans Fear Alex Johnson Has Torn ACL Again

If true, Johnson will likely need to undergo his sixth knee reconstruction.

Sydney fear Alex Johnson has torn the ACL in his "good" right knee and will require a sixth reconstruction in a shattering development for the luckless backman.

Johnson limped from the ground in the arms of the trainers during the first quarter of Sunday's clash with Melbourne at the MCG.

The 26-year-old's knee buckled underneath him when he changed direction while pursuing Jesse Hogan in the forward pocket.

Johnson struggled to leave the field. Image: AAP

Johnson was clearly emotional while being treated on the interchange bench before joining his teammates for their quarter-time huddle.

He's undergone five reconstructions among a total of 12 knee operations but last week returned to play his first game since the 2012 grand final - a period of 2136 days.

"It's the knee he hasn't had any trouble with ... at this stage, it looks like an ACL," Sydney football boss Tom Harley told the Seven Network.

"He's certainly a much-admired character so it's disappointing for him."

Johnson received treatment on the field following the incident. Image: AAP

Johnson has managed just 47 AFL games since being picked by the Swans in the 2010 draft.

He was delisted in 2017 but the Swans then used their final selection in the rookie draft to keep him on their books.