The 13.10 (88) to 7.10 (52) win leaves the firming favourites for this year's flag undefeated after eight rounds, while the undermanned Saints, who worked hard to the final siren, slip to 4-4.
But West Coast faces a nervous couple of days after Chris Judd was involved in an incident that left Saints' tagger Steven Baker on the ground from what appeared to be an elbow from the Brownlow Medallist.
West Coast led from the start, with West Coast forward Michael Gardiner kicking four goals in the first half as the hosts put it beyond doubt early, leading by 19 points at the first break and 43 at the half.
At the other end of the ground, Adam Hunter did a good job on Nick Riewoldt as the West Coast defence stood tall, although they were greatly assisted by St Kilda's lack of system as they went into the forward 50.
The Saints were missing Aaron Hamill, Aussie Jones, Robert Harvey, Justin Koschitzke and Xavier Clarke, while West Coast didn't have Phil Matera or David Wirrpunda, but St Kilda did get back Fraser Gehrig from suspension. But it was disappointing return by Gehrig to his former stamping ground, with last year’s Coleman medallist failing to kick a goal.
Dean Cox comprehensively beat Cain Ackland in the ruck, further advancing his claims as the league's top ruckman, and the midfield he fed profited.
West Coast made its tackles stick while escaping far too easily from attempted Saints grabs, and Chad Fletcher, Ben Cousins, Michael Braun and Daniel Kerr racked up stats at will.
Luke Ball shone for the Saints in the midfield while Sam Fisher was good across half-back and Nick Riewoldt worked hard forward, although his kicking for goal let him down.
West Coast lost Andrew Embley after 15 minutes when he knocked himself out when his head hit the ground in a tackle, but he returned in the second and kicked a ripper not long after getting back on the ground.
After kicking the first four of the match before the Saints snared one just before quarter time, West Coast kicked five goals to one in the second.
Honours were shared in the third term with a couple of goals each, and while St Kilda kept working hard to the end, kicking three goals to two in the last.
St Kilda coach Grant Thomas said that the Eagles were just too good, especially when a number of his players were below their best.
"They were far too good," he said.
"We weren't good enough in a lot of areas. We had too many guys that obviously just weren't up to their normal game for us…it’s a very hard game to win over here, especially with a side that's undefeated and playing very well.
"We needed everyone to make a significant effort and contribution… unfortunately we didn't have enough of those guys."
Next week, St Kilda takes on Adelaide at Telstra Dome while West Coast is at the MCG to play Collingwood.
WEST COAST:4.3, 9.5, 11.7, 13.10 (88)
ST KILDA: 1.3, 2.4, 4.7, 7.10 (52)
GOALS – WEST COAST: Gardiner 4, Cousins 2, Fletcher 2, Sampi, Hansen, Embley, Cox, Jones ST KILDA: Milne 3, Riewoldt, Ackland, McGough, Blake
BEST – WEST COAST: Fletcher, Gardiner, Cox, Cousins, Braun, Glass ST KILDA: Ball, Fisher, Riewoldt, Hayes, Hudghton, Milne
INJURIES – WEST COAST: Embley (concussion), Braun (ankle) ST KILDA: Maguire (calf) CHANGES – WEST COAST: Wirrpunda replaced in selected side by McConnell ST KILDA: REPORTS -
UMPIRES - McBurney, McLaren, McInerney
CROWD - 41,177 at Subiaco Oval
