IT IS season on the line for both West Coast and Fremantle in Derby 53 as both teams ride rollercoaster form lines that have had more troughs than peaks lately. Nathan Schmook breaks down the keys to Sunday's must-win clash. 

The highest-stakes Western Derby in years 

With a percentage that has taken repeated beatings this season, West Coast needs to win to remain in control of its finals destiny. Fremantle, meanwhile, is a mathematical chance only, needing to go 2-0 in the final fortnight and make up a massive amount of percentage. The stakes are as high as they've been in 18 years when the round 22 derby of 2003 cost West Coast a top-four spot and allowed the Dockers to host their first ever home final. This week, there is a risk both teams could be missing from finals for the first time since 2009, so the stakes are different but high nonetheless. 

Who dares wins 

This applies equally to the Eagles and Dockers. The final 20 minutes of West Coast's loss to Melbourne showed it what is possible when it plays with freedom, dare and run, in contrast to the careful approach it has too often had this season. The Dockers, meanwhile, played their best football against Brisbane early in the third quarter when they went direct to tall targets Matt Taberner, Josh Treacy and Lloyd Meek, resulting in contested marks and set shot goals for all three. The lesson wasn't lost on Justin Longmuir post-match, and Adam Simpson was also hopeful his team's daring patch would continue into Sunday's derby.

Freo's pressure point 

Longmuir acknowledged that a trade-off for playing three tall targets forward, including one who is a genuine second ruckman in Meek, was the drop-off in forward pressure. The Dockers' recent tackle numbers inside 50, however, are not sustainable. They lost the indicator 6-25 against the Lions, 3-14 in a win against Richmond, and 2-28 against Sydney in round 19 when Meek first returned to the team. Outside their three talls, the Dockers are playing small and mobile forwards who carry more of the burden to apply pressure when the ball comes to ground. They need to lift. 

West Coast's missing interceptors 

Some of the Eagles' most dominant performances in recent seasons have revolved around gun defensive duo Jeremy McGovern and Tom Barrass dominating the air with intercept marks and launching scoring chains. But it's been an element of the team's game that has been watered down significantly this year, firstly due to injuries to both and then form issues when returning. Barrass returns this week and McGovern has played seven games back since a mid-season knee injury. The Eagles would love to see McGovern, who missed the round seven derby, get closer to the form that saw him lead the AFL for average intercepts in 2019. 

What have the Eagles learned about injury management? 

Barrass (hamstring) is not alone in returning from injury this week, with captain Luke Shuey (calf) and Liam Ryan (hamstring) joining him on the way back in the Eagles' revolving selection door. As Simpson noted this week, they wouldn't put their hands up if they weren't ready, but the Eagles have been burnt this season when bringing several players back from injury at once, most notably when Brad Sheppard, Jack Petruccelle, Tim Kelly, Shuey and McGovern all returned for the 55-point loss to the Western Bulldogs in round 15. In round 22 with their season on the line, it would be a brave call to overlook the trio when they are physically ready. 

How do the Dockers cover Brayshaw? 

Suspended midfielder Andrew Brayshaw has been Fremantle's most in-form player in recent weeks, ruckman Sean Darcy included, and his one-match suspension was a bitter blow the Dockers could not afford. His absence after playing all but one game this season leaves a hole that will not be easy to fill, and the Dockers will turn to Connor Blakely and Darcy Tucker to play more minutes inside the contest. Adam Cerra, Caleb Serong and David Mundy will become even more important, but from there options are limited. Serong should be asked to hunt the ball in the manner Brayshaw would and Mitch Crowden or Bailey Banfield called on to play an accountable role. 

Which Eagle do you tag? 

If locking down on one of the Eagles' stars is the path Longmuir chooses, where does he send his stopper? Glendinning-Allen medallist Tim Kelly thrived in the round seven shootout with 42 disposals (22 contested) and 13 clearances – all career-highs – and would be a worthy target. Shuey can be the most damaging Eagle on his day and is returning from injury, while Yeo entered what Simpson called "beast mode" last week with 31 disposals and 14 clearances in his best game since recovering from osteitis pubis. Whoever the Dockers choose, they will have their work cut out for them. 

The ruck battle 

Always a fascinating aspect of derbies given the calibre of ruckmen both teams have been blessed with over the years. Sunday pits star Nic Naitanui against young challenger Sean Darcy, with plenty at stake for the individuals as well as their teams. Darcy's rapid rise this season has him closing in on Naitanui, and both are in the mix for selection in the Therabody AFL All-Australian team. Naitanui's season has been excellent, dominating the centre square in typical fashion to claim top position in the AFL Player Ratings. Darcy, meanwhile, is dangerous around the ground, gathering disposals and pushing forward to kick goals. How both are supported will be important, with the Eagles turning to all of McGovern, Oscar Allen and Nathan Vardy in recent weeks. The Dockers have Meek as a forward/ruck.

Isolating the advantage 

Both clubs have been required to follow Western Australian government quarantine direction orders and quarantine at home for 14 days after recent interstate trips.  The Dockers emerged from theirs this week and believe it will aid their performance, allowing players to re-engage in aspects of their preparation and recovery they prefer to do away from the club. The Eagles are halfway through their stint since returning from the trip to Melbourne to face Collingwood and are restricted to their homes and the club. Dockers assistant Josh Carr, who breached the quarantine orders, is back at the club after being stood down during the quarantine period. 

Home crowd factor 

The biggest attendance for a Western Derby since the COVID-19 pandemic hit is expected at Optus Stadium, which will have no crowd restrictions in place. Attendance could also be boosted by the fact the round seven derby was played at an empty Optus Stadium after the WA government locked out fans on the morning of the game due to a COVID-19 case in the community. Last year's sole derby attracted a restricted crowd of 25,306, while the Dockers' home derby in 2019 was played in front of 56,358 fans. The highest attendance at the venue this season was for the Dreamtime game between Richmond and Essendon, which drew 55,656 fans and showcased Optus Stadium to the country. A bumper crowd could be what Fremantle needs to gain an advantage, with both teams riding form rollercoasters and in need of a spark.