A sluggish St Kilda continued their unbeaten start to the season with a hard-fought 20-point AFL victory over West Coast at Subiaco Oval on Sunday.

The Saints were uncharacteristically sloppy and looked off their game for the opening three quarters following last week's epic against Geelong.

And the ladder leaders appeared in trouble when West Coast booted five goals to three in the third quarter to level the scores at the final change.

But led by a four-goal haul from Stephen Milne, St Kilda slammed through five unanswered goals to start the final quarter to run away with the 13.12 (90) to 11.4 (70) win.

To add salt to the wound for West Coast, ruckman Dean Cox, returning from a groin complaint, failed to front up for the final quarter and had a noticeable limp, while sharp-shooter Mark LeCras injured his left shoulder late in the match, although he did return to the field.

St Kilda's fifth straight victory lifts Ross Lyon's charges two games clear of second-placed Geelong, who suffered a shock loss to Brisbane on Saturday night.

Leigh Montagna (43 possessions) had the ball on a string while Nick Dal Santo booted three goals and tallied 28 touches and Michael Gardiner won his ruck duel against Cox.

West Coast midfielder Chris Masten (27 possessions) threw his body around at the stoppages, Quinten Lynch was prominent in his ruck/midfielder role and defender Eric Mackenzie restricted danger forward Justin Koschitzke to just eight possessions and no goals.

Nick Riewoldt gave St Kilda the perfect start with a goal inside 13 seconds but the Saints were uncharacteristically lethargic and wasteful in a drab opening term, which was only brought to life when Darren Glass and Milne engaged in a fierce off-the-ball wrestle.

The Saints edged to a 15-point lead early in the second quarter courtesy of a clever snap from Farren Ray but West Coast stormed back into the contest, with two goals from Josh Kennedy closing the margin to four points.

Dal Santo was a shining light amongst the sloppiness, with his two goals for the first half, both from tight angles on the boundary line, helping the Saints to a 10-point advantage at the long break.

West Coast launched a stern challenge in the third term and opened up a seven-point lead courtesy of two goals apiece to Embley and Mark LeCras.

But Milne bobbed up for two important goals to stem the damage.

And the slippery forward helped ice the contest in the final quarter as West Coast turned to rabble.

Milne and Robert Eddy booted two goals apiece as West Coast struggled to clear their defensive 50, let alone launch any meaningful attacks.

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