St Kilda captain Nick Riewoldt rates the condition of his left knee just six out of 10 and says he will most likely need post-season surgery.

But it will not stop the star Saint, who booted a season-high five goals as his team kicked their highest score of the year in downing North Melbourne on Saturday night, playing a major part in the club's finals campaign.

St Kilda ensured their berth with the runaway 19.21 (135) to 10.10 (70) victory over the Kangaroos at Etihad Stadium.

"Clearly it's not like it was when I was 21, but I'm still able to get out and train and function," Riewoldt said of his knee on the Seven Network's AFL Game Day on Sunday.

"I'll maybe have a little bit of a clean-up at the end of the year.

"Out of 10 it would probably be a six, six is alright.

"I don't think you'd find any footballer in the competition, if you asked them about their body, I don't think anyone would give you a nine or 10."

Despite media criticism of his form in the lead-up to Saturday night's match, Riewoldt said even before that five-goal haul, he had been relatively happy.

"That's one thing I've always prided myself on, my ability to prepare and contribute and I think I've done that well this year, I don't think it's probably been as bad as a lot of people have made out," he said.

The Saints have won seven of their past nine games, kicking their four biggest scores of the season in that time and Riewoldt said that was no accident.

"The second half of the year we've really changed the way we've played in a lot of respects," he said.

"We've always been criticised for not being a high-scoring, attacking team, but some of the scores we've been able to put on the board in the second half of the year have been really good."

With Stephen Milne (four goals), Adam Schneider and Justin Koschitzke (three each) also sharing the spoils, coach Ross Lyon said the Saints' attack was in dangerous form.

And afterguiding them to an equal club-record fourth consecutive finals campaign, Lyon, who praised Riewoldt's "magnificent leadership", was clearly excited about the opportunity.

"September's coming and when you've been there, the nostrils are flaring a little bit," a rejuvenated Lyon said.

"The question is have you got the desire and hunger to do what's required to get there, because it's a brutal competition."

The losing grand finalists of the past two years have already shown plenty of heart, reigniting their season, after just one win and a draw in their first seven games, but Lyon warned it was about to get tougher.

"You don't limp into finals, no one sends you a voucher through the mail. You've got to get it done," he said.

"I thought just because we did it tonight, don't assume we're going to do it next week."

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