The midfielder suffered the injury during his side’s loss to Port Adelaide on the weekend.
Despite playing out the game, scans on Monday revealed lateral collateral ligament in his right knee.
Ward missed all of last year after rupturing his ACL, however, the setback is to his other knee.
“We’re really disappointed for Wardy,” Giants head of medical Cullan Ball told the club website.
“He kicked around his body and had that kick smothered.
“He did some damage to his lateral collateral ligament in his right knee, so that’s not the one he had reconstructed last year which we’re thankful about.
“We expect he’ll probably miss four to six weeks depending on how quickly he settles down but thankfully no need for surgery.
“We saw him this morning and he was in really good spirits and ready to crack in to his rehab.”