Sydney Swans ruckman Kurt Tippett has injured a hamstring tendon behind his right knee in his team's clash against rivals Greater Western Sydney at Spotless Stadium on Sunday.
Tippett appeared to aggravate it landing in a centre bounce ruck contest during the second quarter.
The Swans star headed straight into the rooms and did not return to the field.
Coach John Longmire said post-match that the immediate future didn't look good for his ruckman.
"It's a hamstring behind the knee, so I think it's going to be a significant one," he said.
"We don't know (how bad the injury is); that's as much as we know at the moment.
"We haven't got him scanned yet so we won't know until tomorrow (Monday)."