Rosa was injured laying a tackle during the third term of the Eagles' 28-point loss to the Sydney Swans at Patersons Stadium on Sunday.

 

The midfielder, who signed a two-year contract extension during the week to stave-off potential free agency, played no further part in the match and had his right arm in a sling post-match.

 

Eagles coach Adam Simpson feared that Rosa would miss a number of weeks.

 

"He is in a bit of strife," Simpson said.

 

"We think he has hurt his pectoral muscle. So it will be multiple weeks.

 

"We will find out tomorrow. It's early stages but it is not good."

 

Rosa's loss compounds a terrible run during the past month for West Coast. The Eagles have already lost Scott Selwood to an ankle injury, Elliot Yeo to a broken hand, Mitch Brown to knee and ankle injuries, and Darren Glass to retirement.

 

The Eagles may also lose Josh Kennedy to suspension. The vice-captain will be face a nervous wait until the Match Review Panel reviews his head-high hip and shoulder on young Swan Zak Jones.

 

Jones was subbed out of the game with concussion.

 

Sunday's loss to the Swans leaves the Eagles three games outside the eight with seven matches remaining.

 

Simpson conceded his side would struggle to make it to September but he was adamant the Eagles would not put the cue in the rack.

 

"It is going to be difficult with teams around us winning and we are still not finding a way," Simpson said.

 

"But we won't change the course we are on. We will give opportunity to players that deserve it and we will keep managing our older players. The players want to win, so we are still going out there each week to win."

 

The management of the Eagles' ruckmen has been a topical issue in recent weeks. Nic Naitanui was a late withdrawal on Sunday due to general soreness, with Dean Cox and Scott Lycett teaming up against the Swans. 

Simpson said Naitanui needed a break as he was battling back, groin and Achilles issues.

 

"He is just a bit sore," Simpson said.

 

"We gave him every opportunity. The rain as well was a factor in our decision.

 

"Normally big fellas take a few more days to recover.

 

"I have said it before, (he's had) no pre-season in the last two years and he's played every game.

 

"We thought it was the right thing to do."