West Coast have revealed that Oscar Allen's knee injury is worse than first thought, while emerging midfielder Elijah Hewett is also set for a lengthy stint on the AFL sidelines.
Scans earlier this week showed Allen had bone bruising on his knee, but it has since been discovered there is also some cartilage damage.
West Coast released a statement on Thursday confirming Allen will require a minor arthroscopic procedure in the coming days to trim the cartilage, ruling him out for a minimum of eight weeks.
A follow-up scan in a month's time will give West Coast more clarity on when Allen can return.
In more bad news, second-year midfielder Hewett will be sidelined until about the mid-season bye after the sesamoiditis issues in his feet didn't respond to the rehabilitation exercises prescribed by a Melbourne ballet therapist.
The 19-year-old will have surgery next week.
"When we have more information on the rehabilitation progress of both Elijah and Oscar and projected timelines to return we will provide a further update," West Coast football manager Gavin Bell said in a statement.
"This is very disappointing for both players, but we will support them as they work towards a return to play."
Premiership duo Liam Ryan (hamstring) and Dom Sheed (foot) are up to four weeks away from a return, while ruckman Matt Flynn will be sidelined for at least seven more weeks after undergoing hamstring surgery.
West Coast will be aiming to rebound from their 50-point loss to Port Adelaide when they host GWS at Optus Stadium on Sunday.
Ryan Maric is expected to replace Allen in West Coast's forward line.
