WEST Coast has copped a fresh blow ahead of a crucial Western Derby with dashing defender Jackson Nelson ruled out for a month due to a broken wrist.

The injury news compounds confirmation that hard-working forward Jamie Cripps will be sidelined for two months by a nasty ankle sprain.

However, star midfielder Andrew Gaff (ankle) and tough backman Brad Sheppard (knee) are expected to be fit to face Fremantle, while veteran Sam Mitchell (ankle) is pushing to return to play in his first Derby. 

The trio will all be tested later this week ahead of Saturday night's game.

Nelson fractured his wrist during the second term of Sunday's demoralising loss to Hawthorn at the MCG, but the emerging youngster played out the match and finished with 17 touches and five tackles. 

"Jackson Nelson suffered a fracture to his wrist in the course of the game, (he) played it out really well," football manager Craig Vozzo told westcoasteagles.com.au.

"But it’s pulled up sore so he’ll be out for about a four-week period."

Cripps twisted his ankle in the dying minutes of the Hawthorn defeat and was on crutches post-match. 

"Unfortunately it’s a fairly high-degree injury with that ankle and he’s likely to miss a period of about eight weeks, we’re thinking," Vozzo said.

Electric small forward Willie Rioli would be an ideal replacement for Cripps, but the mature-age recruit it still about a month away after hamstring tendon surgery.

Veteran big man Drew Petrie is also another five-to-six weeks away as he recovers from a broken hand, while young midfielder Luke Partington will miss "a couple of weeks" after fracturing his hand playing for East Perth at the weekend.