The Perth Scorchers have been hit by a double injury blow ahead of their qualifier against the Sydney Sixers on Saturday evening.

The winner of the game between the two runaway table-toppers will move straight into the grand final, while the loser will be forced to play the winner of the Melbourne Renegades and Brisbane Heat during the week.

The winner of the qualifier will also earn hosting rights for next Saturday night's grand final.

But the Scorchers, who host the qualifier after topping the table, will be needing to do it without two of their best, with Matt Kelly joining Jhye Richardson on the sideline.

The men in orange have played without Richardson for most of the season, with the star unable to return from a hamstring injury which was suffered against the Sydney Thunder on January 4.

The injury has ruled him out of the last seven games for the Scorchers, and there were hopes he would be able to return for the finals, but he is yet to be cleared as fit.

He had taken 15 wickets in the first 7 games of the season.

"We feel like the depth of our squad is something that's held us in really good stead for a number of years now and this Saturday is no different," Scorchers captain Ashton Turner said.

"For someone like Jhye, who adds so much value to West Australian cricket (and) Australian cricket, there's probably a bit of a longer-term plan with someone with his skill set that he possesses and there's probably no need to take unnecessary risks.

"While we wanted him to play and we know how much value he can add to our Perth Scorchers team, the health of all of our teammates is so important and Jhye is no different and he's just hasn't got ready to play."

Kelly, meanwhile, will miss the game after suffering a concussion against the Melbourne Renegades last Sunday. It's hoped he too will be available for the Scorchers' next game, but he is yet to pass through the protocols for a return to play from a concussion.

"Matt has been progressing through the concussion return to play protocols and is doing well overall. He will not be ready for tomorrow, but we are expecting him back to full training shortly after," WA Cricket State Medical Officer Dr Tom Hill said.

The match will be played on Saturday evening at 7:15pm (AEDT).