SYDNEY midfielder Isaac Heeney looks likely to miss Thursday night's important clash against Geelong at the SCG with concussion.

The Swans will give the gun youngster time to prove his fitness over the next couple of days, but he's not expected to do much training at the club's last session on Tuesday.

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Heeney gathered just five possessions in last week's loss to Richmond at Etihad Stadium after copping a knock in the second term, and played virtually no part in the second half.

The 22-year-old was given a concussion test at the main break and passed all of those protocols but experienced some delayed symptoms during the third quarter and was taken from the field.

Coach John Longmire said Heeney was still a chance to face the Cats but as of Monday, he still wasn't back to feeling his best. 

"He's OK (at the moment), we'll make a decision in the next couple of days whether he plays or not," he said.

"You'd have to say he's in doubt."

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Along with the prospect of Heeney missing the Cats game, the Swans have already ruled out Tom Papley (hip flexor), Sam Reid (quad) and Lewis Melican (hamstring).

Papley missed the loss against the Tigers with a hip problem he's been carrying for a few weeks now, and Longmire said the club is targeting a return for the small forward against North Melbourne in round 17. 

"We wanted to take the opportunity to get him absolutely right," he said. 

"We just feel as though if we played him now, he'd be at risk of re-tearing his hip flexor, which is not what we want." 

The Swans will continue a conservative approach with Reid and Melican, who both haven't played since going down in the dying stages of the club's win over the Giants in round three. 

The pair returned on limited minutes in the NEAFL last week, with Reid particularly impressive early with two goals.

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"We mapped out a plan for both Sam and Lewis and that plan went out the window five minutes into the reserves game because Sam was actually playing really well," he said. 

"We were thrilled that they were able to get through, but it was essentially like a light session compared to what they'd be faced with against the Cats this week at the SCG.

"We didn't want to take that risk even though they pulled up well."

The potential loss of Heeney's hardness around the footy will hurt Sydney's midfield, with the onballer ranked fourth at the club for contested possessions and clearances.

Unheralded midfielder George Hewett is ranked third in both categories behind Josh Kennedy and Luke Parker, and he'll have another important role on Thursday night.

Hewett has been used to run with the opposition's best onballer this season, but with Brownlow medallists Patrick Dangerfield and Gary Ablett, and six-time All Australian Joel Selwood to choose from, he's in for a tough night against the Cats. 

"We've told him to play on Dangerfield or Selwood, and if those two aren't there to go to Ablett, so he's got a big task ahead of him, George, but he's looking forward to that challenge," Longmire said with a laugh. 

"So far, he's been responding to those challenges really well, but his week will be another big one.

"The Cats are very good when they get it because all of those players can win the ball, and when they do win it cleanly they can be really damaging."