All-Australian defender Jeremy McGovern has become the latest West Coast player to enter the AFL's health and safety protocols as coach Adam Simpson prepares to make up to another six changes this week.
McGovern, Nic Naitanui (knee), and Luke Edwards (groin) have all been ruled out of Friday night's clash with Sydney at Optus Stadium, and Simpson says there will be more outs when the team is announced on Thursday evening.
Simpson confirmed star midfielder Elliot Yeo (calf) would return after making it through a WAFL hit-out unscathed last week, while skipper Luke Shuey (protocols) and Tim Kelly (hamstring) are also expected to be named.
Premiership goalsneak Jamie Cripps (pec) and former Blue Sam Petrevski-Seton (calf) could also earn recalls.
Naitanui won't return until the second half of the season after injuring a medial ligament in his left knee.
His injury means Bailey Williams will shoulder the bulk of the ruck work, with support from former Docker Hugh Dixon.
McGovern has been in hot form this season, with his heroics in defence helping West Coast restrict the damage when they were without a host of stars over the first three rounds.
Last week, McGovern produced yet another herculean display to guide West Coast to a shock 13-point victory over Collingwood.
"He's in career-best form Gov, and that's on and off the field," Simpson said of the four-time All-Australian.
"His ability to stand up from a leadership point of view - I think he's gone to another level.
"Sometimes being a good leader, it's hard to play well at the same time. I think he's grown so much in that role. He's a big out."
Yeo injured his calf during West Coast's first pre-season hit-out, and Simpson said it was important to manage the midfielder's minutes carefully.
"We'll need to look at his minutes and how we transition him back into the seniors," Simpson said.
"That won't take one week, that will take several weeks.
"He's in good condition - a lot different than last year (when he was recovering from osteitis pubis), but we need to keep an eye on him as well."
Sydney (3-1) will be without veteran forward Lance Franklin (finger).