Melbourne's weather wasn't the only force causing damage on Saturday as St Kilda thrashed Fremantle by 70 points to secure a berth in the AFL pre-season final.

The collapse of a section of roof during the heavy storm that lashed Melbourne in the afternoon forced the match to be delayed by 20 minutes while an inspection was carried out on public areas.

Supporters were locked out until just before the game began and were confined to the ground level when finally let in as the middle and top tiers were declared off limits to the public.

The delay had no impact on the Saints, who began with a goal inside the first minute and strolled to a commanding 2.15.7 (115) to 2.3.9 (45) win, while the Dockers played like they had hoped the storm would wash the game out.

Goalsneak Stephen Milne kicked four goals for the second game in succession, Clint Jones had a picnic with 40 disposals in midfield and Jason Gram had a big impact with his penetrating kicking and three goals, including a nine-pointer.

The Saints will now play the Western Bulldogs at Etihad Stadium next weekend, after stadium management said the damage to the southern end of the ground was unlikely to disrupt any coming events.

The Bulldogs beat Port Adelaide by three points on Friday night.

St Kilda rested skipper Nick Riewoldt and fellow star Brendon Goddard, but even still there was a gulf in skill.

The Saints booted the first four goals of the game, stretched the lead to 35 points at half-time and powered away with four goals to one in the final quarter.

Fremantle's skill errors crept up alarmingly during the second quarter, and were highlighted by Garrick Ibbotson's dropped mark in the goalsquare, which allowed Rhys Stanley to boot a goal off the ground.

The Dockers' only ray of light came at the start of the third quarter, when Anthony Morabito and skipper Matthew Pavlich dobbed nine-pointers within the space of four minutes.

Youngsters David Armitage and Jarryn Geary (two goals) were also good for St Kilda, as was Sam Gilbert in defence and midfielder Nick Dal Santo.

Pavlich had little impact in his comeback game aside from his long bomb, and the Dockers were best served by midfielder Paul Duffield, Michael Barlow and Kepler Bradley, who tried hard in the ruck.

The AFL confirmed the Saints and Bulldogs would play next Saturday at 7.10pm (AEDT) at Etihad Stadium.

St Kilda's win came at a cost, as vice-captain Lenny Hayes suffered a corked calf, while utility Jason Blake was withdrawn because he experienced back tightness.

Saints coach Ross Lyon said Hayes' injury took the gloss off the win, and that the midfielder would not play the Bulldogs, although he should be available for the start of the season proper.

"We're excited to be in a quality game and it can help with membership and some prizemoney and we stay in Melbourne, we don't travel and stay in front of what should be a full house," Lyon said.

"So there's a lot of positives if you exclude the Lenny hiccup."

Fremantle coach Mark Harvey was disappointed by his side's turnover count.

"Whilst St Kilda played well we made life a lot easier for them out there," he said.

"When you've got younger players in your side and you're not generating enough drive and you struggle to control the ball yourself it can be difficult." Harvey said the Dockers badly missed ruckman Aaron Sandilands, but did not regret resting the big man ahead of round one.

Brought to you by AAP © 2024 AAP