NEXT week's Sydney derby looms as do or die for Greater Western Sydney, with a win required to keep the club's slim finals hopes alive.

Leon Cameron's men entered Saturday afternoon's clash against Port Adelaide with the opportunity to push ever-closer to a debut finals appearance but weren't able to hang in the contest for long enough.

Cameron said slow starts to each quarter and a disappointing period in the final term ultimately led to the 21-point loss.

If the GIANTS can upset the Swans next week, victories over Carlton and Melbourne in the remaining two games could still secure the club a place in the top eight.

"The task next week is the Swans, so who knows what's going to happen, but we need to win," Cameron said.

"We know they're a top-four side when they're at their best … the challenge for us is to get up again after a big match.

"End of next week on Saturday afternoon, it tells me how resilient our players are at the back end of the year, right at the back end."

But the GIANTS will likely have to take on their closest rival without co-captain Phil Davis, who was subbed out against Port with a hamstring injury.

Davis will be assessed in coming days but Cameron said initial signs didn't point to a speedy recovery.

"He came off pretty distressed so you'd have to think it's probably a bad hamstring, [it] might be three weeks," he said.

"That's disappointing, but we've got young guys like Caleb Marchbank, Lachie Plowman and Adam Tomlinson itching for a go and one of them is going to play next week."