Dylan Windler is in pain, but the Perth Wildcats will give their star import right up until tip-off to prove his fitness for Saturday night's do-or-die semi-final showdown against the Sydney Kings in Perth

Windler has been carrying a plantar fascia injury to his left foot for a chunk of the NBL season, and he crumpled to the floor in pain during the dying moments of Perth's heartbreaking 105-104 loss to the Kings on Wednesday night.

The 29-year-old immediately ripped off his shoe to assess the damage before being carried down to the change rooms.

With Sydney 1-0 up in the best-of-three series, the Wildcats are desperate for Windler to play game two at RAC Arena on Saturday night.

But with just three days in between games one and two, Windler's chances appear slim.

"I don't want to say yes or no, because he's been in this moment before and he showed up game day ready to go," Rillie said on Friday.

"It's just something that he's been battling with all season. You can see he re-aggravated it in game one.

"We'll give him as much time as necessary to give himself a chance."

Windler has averaged 13.2 points, 6.8 rebounds and 2.3 assists per game this season.

The American highlighted his importance to the team with a 17-point haul against the Kings in game one, including 5-of-8 from the perimeter.

"People recognise when he's not out there on the floor for us," Rillie said.

"And from both ends - with his three-point range, his ability to live in the paint, make some good decisions, but then also defensively in his rebounding.

"He makes a lot of things tick for us. So if he doesn't play, it's just opportunity for other guys to step up."

The Wildcats were down by one point against the Kings with 11.9 seconds remaining, but their frantic attempt to win fell short.

Kristian Doolittle missed a tough shot to put the Wildcats ahead, Joe Lual-Acuil couldn't make his own shot after snaring the offensive rebound, and David Duke's tricky tip-in attempt was off the mark.

Rillie has been criticised for not calling a time-out before that final play, but it's a tactic he's used all season and is sticking by it.

"I sleep easy," Rillie said.

The Kings are in red-hot form, with MVP runner-up Kendric Davis scoring 35 points in game one.

But Rillie is backing his group to level the series in Perth.

"We've done a tremendous job with our backs against the wall of being able to fight for another day, so I don't expect anything different than that tomorrow," he said.