Liam Duggan will miss the rest of the year after injuring the posterior cruciate ligament in his right knee in the WAFL on the weekend.
Duggan suffered a knock to the knee in a marking contest during the first term of East Perth's win over Perth.
Scans have confirmed damage to the PCL and Eagles' general manager of football Craig Vozzo said that the Eagles are likely to rest Duggan for the remainder of the season rather than push him to return for a potential finals campaign.
"It's very disappointing for Liam and the football club," Vozzo said.
"He's had a terrific first year to date. Liam is going to be a pretty important part of our football club moving forward, so we're not keen to take too much risk with it, which probably means his season is over."