Young Swan Isaac Heeney on Saturday night. Picture:Scott Barbour/Getty Images AsiaPac.

Sydney Swans young gun Isaac Heeney is set to miss up to six weeks of football after injuring his knee in Saturday night’s win against Melbourne.

Heeney ruptured his posterior cruciate ligament in his right knee after landed awkwardly in a marking contest.

The NAB Rising Star favourite will have scans this week to reveal the full extent of the damage, but coach John Longmire said he was thankful Heeny had escaped a season ending anterior cruciate rupture.

“Our doc thinks it’s probably four to six (weeks),” Longmire told reporters post-match. “That’s obviously straight after a game – he hasn’t had a scan yet – but that’s the early diagnosis … Hopefully that’s a good sign,” Longmire said.