SOMETIMES footy can be so cruel.

One week after returning from five knee reconstructions, Sydney defender Alex Johnson looks set to undergo a sixth.

The premiership player was chasing Jesse Hogan in the first quarter of the Sydney-Melbourne game at the MCG when he went to change direction and immediately hit the deck.

The look on his face said it all, and his teammates, opponents and the crowd all looked to share his concern.

Swans football boss Tom Harley told Channel Seven it looked like Johnson had done an ACL again.

Johnson could barely contain his emotions on the bench, with his career now most likely over after years of work to get back to the elite level.