GREATER Western Sydney has been dealt a blow with star midfielder Josh Kelly ruled out of Sunday's crucial clash with Richmond at the MCG.

Kelly injured his left calf in the final quarter of the Giants' disappointing loss to Brisbane on Sunday and is expected to miss at least the next three weeks.

The loss of the gifted onballer is horrible timing for the Giants, who have dropped their past two matches against Essendon and the Lions.

They face the Tigers on Sunday, then take on Collingwood (home), Port Adelaide (away) and Sydney (home) in the next month.

GWS footy boss Wayne Campbell told the Giants' website he's hopeful Kelly can get back for the trip to Adelaide, or the Sydney derby at Giants Stadium a week later.

FULL INJURY LIST Who's ruled out and who's a test?

"He's got a grade one tear," Campbell said.

"It looks like three weeks (out), but it could be a week either side of that.

"At this stage he'll miss this weekend and a couple after that."

The good news for GWS is that the 2017 Kevin Sheedy medallist is likely to be replaced by last year's club champion, with Lachie Whitfield ready to take on Richmond after missing four games with a broken collarbone.

Campbell declared Whitfield – who has been sorely missed by the Giants - a certain starter against the Tigers.

Vice-captain Stephen Coniglio should also be fit for the trip to Melbourne after he was cleared of a serious knee injury.

Coniglio was also a casualty of the Lions loss after hurting his knee just before half-time.

However, he managed to play out the game with his left knee heavily strapped, and remains likely to face Richmond after scans came back with positive news.

"There was no structural damage, he just hyper-extended his knee a little bit and he's pulled up pretty well," Campbell said.

"We'll need to see him train and test him and all that sort of stuff, but there's no major damage and at this stage we expect him to play this weekend."

Ruckman Shane Mumford is also expected to come into the team after he pulled up sore from the Giants' round 15 loss to Essendon and was rested against the Lions.