The Japanese star was ruled out of Friday night's clash against the Newcastle Jets with a groin injury.

Tony Popovic's side require a solitary point from their final-round fixture to seal top spot in their inaugural season.

The coach is confident Ono will be back on deck for his side's semi-final against a yet-to-be-determined opponent in a fortnight.

"We're still hopeful he'll be available for the semi-final, the scans didn't reveal too much damage which was encouraging for us," Popovic said.

"He's in a positive frame of mind and we're still optimistic that he'll be available for that game.

"He's our marquee player and he's our creative spark but when he hasn't been available the players that have come in have done a very good job."

Ono's absence is not the only headache for Popovic.

Adam D'Apuzzo (foot) and Jerome Polenz (quad) are also unavailable, while midfielder Iacopo La Rocca is out for the season after copping a four-match ban for his stray elbow against Sydney FC.

Central defender Michael Beauchamp (quad) and key midfielder Aaron Mooy (knee) are in a race against the clock to prove their fitness, with Popovic insisting he will take a cautious approach with his players ahead of the finals series.

"If they're not fully fit, they won't play," he said.

In at least one piece of good news for the Wanderers, electrifying Dutch winger Youssouf Hersi will return from suspension against the Jets.

The Jets need to win and have results go their way in order to force their way into the finals mix.

Newcastle are currently in eighth spot on 31 points, equal with Perth Glory and one point adrift of Sydney and Brisbane heading into the final round.