Hawthorn coach Alastair Clarkson confirmed the small forward was "under a bit of a cloud" for the clash with the Swans after he failed to train with the main group on Thursday.
Rioli missed last week's trip to Sydney with an ankle complaint.
But Clarkson indicated Rioli would likely still be named in the Hawks side when team sheets are lodged later on Thursday.
The coach said a final call on Rioli's fitness would be made just hours before the bounce.
"He's under a bit of a cloud, Cyril," Hawthorn coach Alastair Clarkson told reporters after the Hawks had a light training run at Waverley Park on Thursday.
"We'll select him in our side tonight and then make an assessment on him probably tomorrow morning.
"He tried to train (on Tuesday) and there was just a little bit of discomfort there so we pulled him back.
"He's done some running ... this morning so we'll wait and see how he pulls up from that and if he's okay, we'll play him.
"If he's not then we won't be taking a risk."
Key forward Lance Franklin trained on Thursday but will miss the first-versus-fourth qualifying final through suspension.
"Outside of 'Bud' (Franklin) being suspended and the cloud over Cyril, we've got a full group to pick from, outside of (Ryan) Schoenmakers (knee) and (Matt) Suckling (knee) who were injured earlier in the year," Clarkson said.
"We've had a great preparation. Our last couple of games, Kangaroos and Sydney (wins by 14 points and 12 points) have been really good finals-preparation games and we feel like we're as well-prepared as we can be."
The Hawks go into Friday night's grand final rematch as the minor premiers with a 19-3 win-loss record and a four-match winning streak. Defending premiers Sydney have qualified in fourth spot and have lost three of their past four games.
Clarkson said last year's grand-final loss to the Swans would motivate his players.
"We're better prepared because we know the outcome of what happened last year so that prepares us and steels us a little bit I suppose," he said.
"We've been able to manage our squad a little bit better this year because we won more early games. That has given us an opportunity when a player has been sore we just haven't played him."
