GREATER Western Sydney has suffered a huge blow ahead of a vital clash with Adelaide on Saturday night, losing young gun Tom Green to injury.

In a ninth-versus-10th cracker, the winner of the Adelaide Oval battle could finish the round inside the top eight and will give their finals hopes a massive boost, particularly after the seventh-ranked Western Bulldogs lost to Sydney on Thursday night.

But the Giants will have to do it without influential inside midfielder Green, who coach Adam Kingsley said did a "slight hamstring" at training on Thursday.

Green is expected to be sidelined for three weeks, with Jacob Wehr replacing him to face the Crows.

"It happened (on Thursday), he was just still a little bit uncomfortable with it, we decided to get a scan and it came back no good," he said.

"So it's unfortunate for us but another guy comes in and he'll get his opportunity through the midfield whoever that is when we decide, and we'll go from there."

The absence of Green, who ranks fourth in the League for disposals, will heap more pressure on the other Giants midfielders, including Josh Kelly who copped a hard tag against Hawthorn last time out and was held to just six touches.

It was just the second time in Kelly's last 162 games he's had single-digit disposals.

"Josh and I sat down about it and spoke about the options that he does have if and when he gets tagged next, whether that's this week or beyond," Kingsley said.

"So he's armed with a few more tools now that will be able to hopefully help his influence on the game be a little greater than what it was against Hawthorn.

"They did a wonderful job on him, and we probably as a team didn't help Josh enough, that's something we'll take out of that game."

The clash will also bring two important milestones, Adelaide's Rory Sloane celebrating his 250th match while GWS' Lachie Whitfield will be playing his 200th.