Kennar in as Johnston ruled out for Souths

South Sydney will put their faith in journeyman Richie Kennar to fill the void left by Alex Johnston after the Rabbitohs winger was ruled out of the NRL preliminary final meeting with Penrith.

Johnston, who sustained a hip flexor injury in last week's win over Cronulla, trained separately from the main group at Redfern Oval on Friday.

The Papua New Guinea international, who has 30 tries in 25 games this season, was put through a late fitness test but will not be risked against the Panthers.

Kennar trained on the left flank, with Souths coach Jason Demetriou confident the 27-year-old could handle the occasion in his second NRL game of the season.

"He (Johnston) is out and he was never going to really be a chance of playing," Demetriou said.

"I'm happy for Richie to get the opportunity. The game suits him because it's going to be physical."

Josh Mansour - the other outside back in the Rabbitohs' extended squad - did not train on Friday, with Demetriou unsure of the Penrith winger's whereabouts.

Kennar, who has previously had stints with Melbourne, Brisbane and Canterbury, registered a hat-trick in his sole game for Souths this year when they defeated Newcastle in round 17.