Greater Western Sydney key defender Phil Davis will miss the rest of the AFL season, having returned home because of a knee injury.

The Giants’ finals hopes took a major blow when they suffered a shock loss to last-placed Adelaide on Tuesday night.

The absence of former captain Davis, who would ordinarily be one of the first players picked to face Melbourne in Saturday’s crunch clash at the Gabba, won’t make things any easier in their run to finals.

GWS hold eighth spot by just 0.9 per cent from the Western Bulldogs, with Giants coach Leon Cameron suggesting this weekend will mark “our first final”.

Cameron indicated midfield star Josh Kelly, who has missed two games after being concussed on August 29, is a chance of returning alongside Zac Williams (achilles), Harry Perrman (calf) and Brent Daniels (hamstring).

Davis, who has been on the sidelines since hurting his left knee in the team’s win over Essendon on August 7, won’t play again in 2020.

The 30-year-old recovered from the setback he suffered against the Bombers but has been unable to train recently because of bone bruising in his right knee.

Davis will undergo a minor operation in coming days then rest for eight weeks.

“Phil has been managing this injury across this season,” GWS football manager Jason McCartney said.

“Unfortunately it’s reached the point where only a long period of rest will fix the problem.

“Phil’s an incredibly important part of our line-up.

“So it’s disappointing for us on field, but this is the best option to make sure he’s fully fit for the 2021 season.”

GWS finish their season with matches against the Demons and St Kilda.

The Giants were widely expected to be premiership contenders in 2020 after reaching last year’s grand final.

They defeated Geelong and Richmond earlier this year but losses to the Crows, Sydney and North Melbourne will likely prove costly in the condensed season.

GWS first-choice ruck Shane Mumford, who was rested against the Crows, will return to battle Melbourne captain Max Gawn in a match Cameron said was season-defining.

“Our first final is on Saturday night,” he said.

“If we can play some really good, hard, tough footy … then you deserve to get there. If you can’t, then you don’t deserve it.”

Kelly will need to prove his fitness at training.

“Josh has got to get through a block of training and also some contact before the doctors give him the green light,” Cameron said.