West Coast could be without crucial midfielder Tim Kelly for several weeks after he joined a growing injury list full of stars with a medial ligament injury on Saturday night.   

The Eagles will also be without young star Oscar Allen for the crunch match against Carlton in round 12 after it was confirmed the important tall had suffered concussion in a 16-point loss to Essendon at Optus Stadium. 

The double blow, which came as dual club champion Elliot Yeo returned but needed to be managed after a long battle with osteitis pubis, has left the Eagles vulnerable after their first loss at home this season. 

Coach Adam Simpson did not want to use injuries as an excuse for the Eagles' second-half fade-out, which saw them surrender a 29-point lead and slip two games and significant percentage outside the top four.

"We weren't tough enough for long enough really," the coach said. 

"Having some players underdone doesn't help when you have two injuries … (but) I don't think we should dwell on that too much. 

"We couldn't win a contest in front of the ball late, they played really well, and they got us on the outside. 

"The will to win was there for the most part, but not the whole part."

Kelly and Allen join captain Luke Shuey (hamstring), four-time All-Australian Jeremy McGovern (knee), premiership defender Liam Duggan (knee), and recruit Alex Witherden (groin) on the injury list.   

Simpson said the in-game setbacks had not altered the way Yeo was played, having headed into the match intending to manage the 27-year-old's game time. 

"He was a bit rusty early and he worked into it. He'll build his minutes, but we've got to manage him for the rest of the year," Simpson said.