Sydney Swans co-captain Josh Kennedy will be sidelined for at six weeks while high-flying forward Isaac Heeney is set to miss the rest of the season, after the pair suffered injuries in Sunday’s loss to Richmond.

Heeney will require surgery after scans revealed he has suffered a dislocation and ruptured the medial ligament in his ankle. 

The prognosis is also as feared for Kennedy, who has ruptured the medial ligament in his knee. While the No 12 won’t need surgery he will be required to wear a brace for several weeks.

Sydney Swans coach John Longmire said it was unfortunate news for Heeney.

"Isaac is having an ankle operation this afternoon as he has a ruptured medial ligament in his ankle and also the tendon tunnel in his ankle has been ruptured," Longmire said.

"He is out for the year as he will be in a moon boot for the next eight weeks.

"Isaac works so hard on his game, he plays a lot of the time with all sorts of injuries no one would know and he is as hard as. 

"When he went down with an injury after the game I knew it was significant because he is tough."

Longmire said the co-captain was disappointed with the news.

"Josh has strained his medial ligament in his right knee so he will be in a brace for probably five weeks,"

"Then maybe he will be right to go by the six to eight week mark.

"He has been fantastic, he and Isaac have been really good for us this year."