GEELONG has secured a preliminary final berth in emphatic fashion, with a devastating third-quarter blitz setting up a 58-point win over St Kilda at the MCG on Sunday.

The air of inevitability that has followed the Cats throughout the season was in evidence throughout the match, as they were rarely challenged on their way to the 17.17 (119) to 8.13 (61) win.

But the victory came at a high cost to the Cats, who lost Brent Prismall in the 17th minute of the first quarter. The 22-year-old was stretchered off and did not return after his right knee buckled under him.

Adding to the injury concerns was the sight of Paul Chapman sitting out most of the second half with a hamstring and a knee heavily strapped.

Jimmy Bartel and Gary Ablett dueled for best-on-ground honours finishing with 34 and 35 possessions respectively, with Bartel booting two goals to Ablett's one. Joel Corey (32) and Darren Milburn (32) were also prolific ball winners. 

Harry Taylor was something of a surprise match-up on Nick Riewoldt, but the 22-year-old impressed in keeping the Saints' skipper to nine possessions and one goal while gathering 23 disposals of his own.

St Kilda had few clear winners across the ground, but Sam Fisher toiled hard for his 31 possessions, while Lenny Hayes (30) and Leigh Montagna (25) worked hard throughout.

Adam Schneider gave the Saints their first and only lead of the day with the first goal of the match five minutes in, but it was all Geelong from there.

With Bartel leading the way around the stoppages, the Cats went inside forward 50 on 15 occasions, and it was only their wastefulness once in attack that saved St Kilda.

Chapman put Geelong back in front with his first, but seven behinds were registered in the first term before Cam Mooney and Bartel finally gave their side a deserved 18-point lead at the first break.

Brad Ottens spent some time up forward in the second, and booted two goals as the Cats stretched their lead.

Mooney's second goal provided a snapshot of the forward line pressure that was in evidence all day. Forced to play on, Jason Blake, who could not find a target downfield, had the ball smothered and then Fisher scooped it up but put it out of bounds on the full. Ablett found Johnson from the resultant free kick, and Johnson placed the ball neatly on Mooney's chest 10m out.

Stephen Milne bobbed up with the first of two goals on the day and Xavier Clarke pulled the margin back to 32 points at half time, but the signs were ominous.

Ross Lyon swung the changes during the break, with Riewoldt starting up on a wing and Andrew McQualter going to Bartel, but they failed to make an impact.

Despite scoring three successive behinds and then conceding a goal to Brendon Goddard to start the half, Geelong took its game to an even higher level in the third term.

Nine goals, including two to Tom Lonergan, rained down on the shell-shocked Saints, who were powerless to stop the run. Ablett was in everything with 12 possessions for the quarter, and added a superb goal as the dominant Cats rumbled to a 76-point lead at the last change.

With the sting well and truly out of the match and with both sides eyeing their next finals encounter, the Saints were at least able to outscore the Cats three goals to one in the final term.