The 2016 All Australian tripped and fell while doing some recovery running with teammates outside the SCG and has a small crack just below his elbow.

Coach John Longmire said losing one of his vice-captains in such unique circumstance was a massive disappointment ahead of Friday night's crucial clash with the Western Bulldogs.

"I sat down did the game review with him about 9.30 this morning, he then went for a run with the team an hour later, jumped over a chain on the way back and landed on his arm," he said.

"At the moment I've been told it looks like a five-week injury.

"I couldn't believe it to be honest, one of our guys from our media department saw it happen.

"He tried to jump the chain and mistimed his jump and fell on the concrete 25 metres from the front door (of the Swans' offices)."

Rampe's injury looks likely to open the door for exciting tall defender Aliir Aliir, who wasn't selected for the Swans' loss to Port Adelaide as he continues his way back from a toe injury.