GEELONG coach Mark Thompson finished his post-match press conference on Sunday with an apology for being boring, but there was nothing mundane about the way his side dismantled St Kilda at the MCG.

Thompson was, of course, referring to his stock answers to the same questions about just how good the dominant reigning premiers can become, but he's fielded such queries so many times now that there was a sense of déjà vu following the 58-point demolition that secured a preliminary final berth.

"We don't want to play better, we just want to play the best we can on a certain day against the opposition that we're playing," Thompson said after the Cats overcame an inaccurate start to lead by 76 points at three-quarter time.

"We've been in some pretty good form. Today the conditions probably didn't help us play our best footy, but in saying that, to kick nine goals on a wet track in a quarter of footy is a pretty good effort.

"It was a funny start; we sort of went wide with our entries, and we were trying to score goals from outside [the 50m arc] … and it's really hard to score from out there. We weren't playing our best team footy, but we were having shots at goal, we were having entry, and the fundamentals were right. Certainly by the time the third quarter came along, we were pretty fantastic to score 9.5 in a quarter of footy."

Thompson revealed denying the Saints forward entries and stopping dangerous forwards Nick Riewoldt and Stephen Milne had been key goals going into the match, and he left the MCG satisfied that those goals had been well and truly achieved.

St Kilda went inside the attacking 50 just 30 times to three-quarter time, finishing with 44 after the heat went out of the game in the last, while Milne and Riewoldt, who combined for 11 goals last week, finished with two and one respectively.

"I thought Josh Hunt did a fantastic job with Corey Enright and a few others who played on Milne for a while," Thompson said.

"I thought together as a group they really helped Harry Taylor [who played on Riewoldt].

"I know he's had a little bit of personal criticism and some people see that [he's] a weakness in Geelong, but we've been really supportive of him. He played a terrific game individually and I thought he got amazing help from his teammates."

The win was soured by the loss of Brent Prismall, whose knee showed early signs of an anterior cruciate ligament tear, and Paul Chapman who will undergo scans to determine whether he has torn a hamstring.

Geelong will play the winner of the Sydney Swans-Western Bulldogs semi-final in the preliminary final.