The final Carlton Draught Derby at Domain Stadium won't live long in the memory, but West Coast banked four vital points as Fremantle missed their chances in front of goal.
West Coast's five-goal-to-nil opening burst proved the difference in a clash overshadowed by Freo's inaccurate goal kicking.
Fremantle had the same amount of scoring shots but no winners in attack as the Eagles ran out 11.8 (74) to 5.14 (44) winners.
West Coast skipper Shannon Hurn was the unanimous choice as Ross Glendinning medallist after picking up 34 disposals across half-back.
Freo's chances of finals football have been dealt a blow and the loss could be soured after star Stephen Hill hurt his shoulder in the final term, although he returned to the action after receiving treatment.
Freo wingman Bradley Hill (28 disposals) found plenty of the ball but had a day to forget in front of goal, missing some sitters as he kicked three behinds.
Skipper Nat Fyfe (30, 19 contested) could hold his head high after fighting all match in the midfield and helping Freo gain some ascendancy after trailing 25-3 at quarter-time.
Kersten with the silky snap #foreverfreo #AFLFreoEagles pic.twitter.com/d9p2k6STRy
— Fremantle Dockers (@freodockers) July 16, 2017
Freo's vaunted onball brigade wrestled its way on top but some wasted inside 50 entries, saw them trail by 14 points at the long break.
Freo notched six behinds before Kersten finally broke the drought with a miraculous no-look snap midway through the second term.
Fremantle refused to go away in the second half, and closed the margin to 16 points in the final quarter, but the Eagles had enough answers.
West Coast wrapped up the history of crosstown rivalries at Domain with an overall 26-20 win-loss record after Sunday's win.
More to come
FREMANTLE 0.3 2.8 3.13 5.14 (44)
WEST COAST 4.1 5.4 9.6 11.8 (74)
GOALS
Fremantle: Walters 2, Kersten, Suban, Ballantyne
West Coast: Kennedy 3, LeCras 2, Darling 2, Petrie, Priddis, McGovern, Sheed
BEST
Fremantle: Fyfe, Neale, Suban, Blakely, Weller
West Coast: Duggan, Hurn, McGovern, Sheppard, Gaff, Redden
INJURIES
Fremantle: S.Hill (shoulder)
West Coast: Nil
Reports: Nil
Umpires: Stevic, Hay, Findlay
Official crowd: 38,722