The veteran attacker is facing another week on the sidelines after sitting out Heart's 2-2 draw against Central Coast
Heart coach John Aloisi conceded on Saturday that Kewell remains in bad shape, following an injury sustained in last week's Melbourne derby where Victory defender Pablo Contreras unintentionally kicked the ball into the back of the forward's head and neck.
Kewell had initially been expected to recover in time for Heart's home clash against Central Coast Mariners but was left out after he failed to train throughout the week and Aloisi has doubts whether the 35-year-old will be ready to take on Glory in Perth on October 27.
"Harry, after seeing him this morning, I'm not sure (whether he will be fit to play Perth)," Aloisi said after Heart's 2-2 draw with the Mariners on Saturday.
"We thought we'd give him every bit of time needed to be ready for this game but he was struggling this morning, so I'm not sure if he'll even be right for next week."
Kewell was diagnosed with whiplash following the Melbourne derby and Aloisi explained that his key playmaker was suffering referred pain through his back and even in his hamstrings.
But in a positive for Heart, Aloisi confirmed Michael Mifsud will be ready to make his debut for the Red and Whites in Perth.
Mifsud has missed the opening two rounds through international duty with Malta and Aloisi argued the 32-year-old striker would be raring to go against Glory.
"Definitely Michael will be (fit)," Aloisi said.
"He played two 90-minute games (for Malta in the past fortnight), which was great."