Sean Darcy has come out of Fremantle’s side for their potentially season-defining clash with Sydney on Thursday night, with Mason Cox instead set to support Luke Jackson in the ruck.

And the Dockers have officially ruled out Hayden Young for the top-of-the-table blockbuster, with veteran midfielder Jaeger O’Meara favoured to replace the injured left-footer.

Darcy has been listed as managed for what will be Fremantle’s third game within the span of 12 days.

The 2021 Doig medallist made his return from a calf injury against Gold Coast in round 16 and backed up to make the trip to Canberra for their streak-snapping loss to Greater Western Sydney on Saturday.

He was not granted an instant AFL recall once he had recovered from the latest setback with his body, instead playing three games for Peel Thunder in the WAFL in order to build form and fitness as Cox deputised for him in the senior side.

The American recruit has played eight AFL games this season, holding his own in the ruck but battling for influence as a forward.

He managed two goals in what was just his second game for the club against Carlton in round seven but went without a major across his next six appearances.

Cox responded to his omission with a pair of strong performances for the Thunder in the last two weeks, including a 30 hit-out effort against one of the competition’s premier big men in Claremont’s Ollie Eastland last weekend.

Meanwhile, Young has not managed to complete his recovery from a minor groin injury within a tight five-day turnaround from Fremantle’s 21-point loss to the Giants.

Earlier in the week, coach Justin Longmuir had flagged the possibility the Dockers could opt to cover for his absence by replacing him with a forward, but O’Meara has instead won back a senior spot he lost after their bye.

Singled out by the coach as being unlucky to find himself on the outer amid an unprecedented recent selection squeeze, the versatile 32-year-old has won 23 disposals and kicked a behind in each of his last two appearances for the Thunder.

O’Meara was one of two travelling emergencies for the Dockers’ trip to the nation’s capital last week, alongside speedy forward Chris Scerri.

Utility Corey Wagner was held over for their win over Gold Coast in round 16 but has been overlooked despite gathering 28 disposals and kicking a goal for Peel last weekend.

Sydney star Tom Papley has been passed fit to return from a calf strain to take on the Dockers, replacing utility Corey Warner in what is the Swans’ only change.

FREMANTLE v SYDNEY

Optus Stadium, Thursday, 6.10pm

DOCKERS

B: B Cox A Pearce H Chapman

HB: J Clark L Ryan K Worner

C: N Erasmus A Brayshaw J O’Meara

HF: M Reid M Frederick S Switkowski

F: P Voss J Amiss J Treacy

FOLL: L Jackson C Serong S Bolton

I/C: J McVee M Johnson N O’Driscoll I Dudley M Cox

EMG: O McDonald B Walker C Scerri

IN: J O’Meara M Cox

OUT: H Young (groin) S Darcy (managed)

SWANS

B: C Mills W Edwards T McCartin

HB: D Rampe N Blakey H Cunningham

C: M Roberts E Gulden J Serong

HF: J Jordon J Lloyd J Rowbottom

F: T Papley C Curnow H McLean

FOLL: B Grundy I Heeney Ch Warner

I/C: H Kyle J Hamling T Hanily A Sheldrick C Cleary

EMG: R Bice Co Warner L Melican

IN: T Papley

OUT: Co Warner (omitted)