Peel Thunder will need to secure wins in all their remaining games of the season to stay within finals contention after suffering a disappointing 31-point loss against West Perth last Saturday.
If the eighth-placed Peel Thunder can win against East Perth this weekend, they will potentially move to fifth place on the ladder.
This will also depend on the result of the Swan Districts and Subiaco game, with a win by the Lions the more favourable outcome for Peel.
Due to new rules implemented by the WAFL for the 2018 season, Peel and East Perth are now restricted to a maximum of 12 AFL-listed players during the finals.
Ahead of round 18, Fremantle have nine players who have qualified for finals, which includes Harley Bennell, Brady Grey, Danyle Pearce, Shane Kersten, Luke Strnadica and first-year players Lloyd Meek, Mitch Crowden, Tom North and Hugh Dixon.
To qualify, players need to have played a total of five matches, including three after 30 June.
In addition, Michael Johnson, Sam Switkowski, Taylin Duman, Cam McCarthy, Scott Jones, Ethan Hughes and Ryan Nyhuis could potentially play in the finals if they join Peel in the remaining rounds of the season.
The final four rounds of the home and away season will see Peel face off against East Perth twice (during rounds 18 and 21).
Peel have a bye in round 19 and the following week will take on Claremont, who are sixth on the ladder and ahead of Peel by percentage.
This Saturday Peel Thunder face East Perth at Rushton Park at 2.10pm.
