North Melbourne will look into the interchange error that cost the club victory in a chaotic finish on Saturday, with the Swans awarded a free kick in front of goals in the dying stages.

Sydney were given a free kick and 50 metre penalty for the interchange infringement, with Hayden McLean converting the set shot to give the Swans the lead late. The infringement occurred when Tom Powell and Hugh Greenwood came onto the ground to replace Liam Shiels and Will Phillips, taking the Kangaroos over the allowed 75 rotations.

While their was initial confusion on the ground and in the coaches box, the error was soon realised.

Speaking after the match, interim coach Brett Ratten said that the club would look into the error in the wake of the three-point loss.

"We'll have a look at it during the week and work out how we can do some things better, but we're not going to worry about that," said Ratten.

"We had our chances. We'll have a look at it, review it and see if we can get better.

"There's sometimes a chat (in the coaches' box) about we're getting close with the rotations but there's nothing from a senior coach's point of view that I'm looking at the interchanges.

"There's so much going on in a game, so no, we just leave that to the bench."

The loss becomes North Melbourne's eighth in a row, while the Swans managed to end their month long losing streak.

Sydney coach John Longmire admitted after the game that they were confused when the free was paid, not knowing what the infringement was.

"We genuinely didn't know what the free kick and 50 was paid for," Longmire said.

"It wasn't until afterwards, someone told me after the siren had gone."

McLean, who kicked the winning goal, echoed those sentiments to ABC Sport post-game, but was thrilled to collect the four points.

"The umpires just kept hold of the ball. I was wondering what was going on, maybe a free kick downfield or something," McLean said.

"And then he just looked at me and said 'Interchange free kick and 50 metres, your kick'. So we'll take that.

"The [shots at goal] in front are always the most nerve-racking. But I was glad to kick it, and it was a good win in the end."