COLLINGWOOD coach Craig McRae was left seething at the decision not to award Daniel McStay a critical 50m penalty in the dying stages against Sydney, after his side had let a match-winning lead slip at the SCG.

Still reeling from the non-call post-match, the Magpies coach said "it would have been paid" had it been at the MCG, while he described the number of insufficient intent calls in the game as "a bit of a circus".

SWANS v MAGPIES Full match coverage and stats

Collingwood led by as much as 27 points in the final term until the Swans stormed home with the last five goals of the match to snatch a three-point victory on Friday night that all but ended the reigning premiers' finals hopes.

Errol Gulden booted a goal to put the Swans in front with four minutes remaining, but the Pies made one last surge as McStay marked just inside the centre square with 40 seconds left on the clock.

Swans defender Tom McCartin trailed behind the hard-leading McStay and ran several metres over the mark, but was fortunate to avoid a costly penalty when only taking a few steps back.

"I reckon if it was at the MCG, it would have been paid. There's definitely an advantage for the home ground," McRae said.

"I thought it was a 50m penalty, to the letter of the law. I'm sure the AFL will come out and say it's a free kick or 50m penalty.

"There was a lot of deliberate (insufficient intent to keep the football in play) tonight too. That was a bit of a circus. So I'm sure they'll come out and justify that too. But the umpires don't always get it right."

The Magpies had a third consecutive victory to keep them in touch with the top eight within their grasp, before the Swans took control in the midfield. 

Isaac Heeney and Chad Warner had come under fire as the ladder-leading Swans slumped to five defeats in their six previous matches, but stepped up in the final term to turn the game against the Pies.

The gun onballers each had 14 disposals and booted a goal in the final term, as the Magpies suffered their narrowest defeat since losing to the Swans at the same venue in a 2022 preliminary final. 

The three-point loss was also the first time the Magpies have lost by under a goal this season, after winning five games decided by less than a kick including in an after-the-siren thriller against the Blues last week, and have been part of a pair of mid-season draws.

"Isaac Heeney, he was pretty special, wasn't he? He was amazing, I don't think I'd seen a player impact a game like that in a quarter. Unbelievable," McRae said about how the game changed.

"I think the game's probably harder than ever to maintain a lead. We're having to go through that in the last couple of weeks of being in a position to win the game, and then having to hold on.

"I'm just reflecting myself now, without the vision in front of me, but thinking maybe the method's not the right one."

Sydney bounced back from a crushing 112-point defeat to Port Adelaide last week to claim a win that ensures it will hold on to top spot as it has done since round seven.

The Swans showed glimpses of their best form as they opened up the Magpies with blistering ball movement when the match was on the line, and could now ensure they host two finals with at least one win in the final two rounds. 

"Really proud of what the players were able to do," Swans coach John Longmire said.

"Sometimes you just need to find a way, and that last quarter was as good a last quarter as I've seen, considering the situation and being able to turn it around and do what we were able to do.

"There's some huge efforts in the last term and Chad and Isaac, their contest, the amount of contests that we won, the 50-50 balls ... it's probably a bit unfair to single out a couple, there was an enormous across the board effort in that last quarter."