Sydney Co-captain Josh Kennedy looks set to for a stint on the sidelines after injuring his knee in Sunday's loss to Brisbane, while star forward Isaac Heeney will undergo scans on an injured ankle.

Kennedy suffered a medial strain after his left knee after it twisted awkwardly in a Marlion Pickett tackle during the first quarter.

“Josh has done a medial, so he will miss a number of weeks, it looks pretty bad,” Coach John Longmire said after the match.

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Longmire post match - Rd 6, 2020

John Longmire speaks to the media after the Round 6 loss to Richmond.

Heeney left the field in the dying minutes of Sunday's loss after rolling his ankle in a tackling contest.

“Isaac is being assessed so I have no idea at the moment," Longmire said. 

“Obviously it was a pretty bad ankle as he is pretty tough and he wouldn’t come off normally unless it was pretty bad.”

Kennedy has been one of the most durable players in the league, missing just six matches since joining Sydney ahead of the 2010 season.