The AFL has defended field umpire Brent Wallace disallowing Nick Watson's goal after the half-time siren on Thursday night.

The decision to call play on as Nick Watson deviated off his line drew the ire of many across the footballing landscape.

"The umpire, positioned directly behind the kick, correctly disallowed the score after Nick Watson moved off his line to the right and didn't kick the ball over the man on the mark," a statement, released on Friday afternoon, read.

"The AFL have contacted Hawthorn and St Kilda today to provide an explanation regarding the decision."

Broadcast angles appeared to show a very minimal deviation, if any at all, prompting criticism that the incident had been over officiated. But a fan sitting behind the Watson kick released vision on social media on Friday which showed he clearly veered to the right of the man on the mark.

The decision had no bearing on the outcome of the contest, with Hawthorn leading by 50 points at half-time and cruising to a 52-point victory.

Hawthorn coach Sam Mitchell expressed frustration about the decision post game.

"We'll certainly be going to the AFL to ask about it. It makes sense to me that that is a rule on the other side of the ground. As a right footer, there is absolutely no reason that a player would go wider to give themselves an advantage, and that's what the rule is there for," Mitchell said post-match.

"And it makes sense, but the vision doesn't look like he goes off his line much, but that's the umpire's call, and I can accept that. But the fact that you can go off the line towards the boundary and it be called play on ... there's no common sense about that.

"So, I would hope that we get an answer from the AFL, and I'm sure we will. They've been very good at giving us answers and giving us adjustments; they've done that really well. When something doesn't make sense, they fix it pretty quickly. So, why would he run wider to give himself a harder shot and get called a play on?. Didn't make a lot of sense, I'm glad it was in a game where individual tiny scores didn't matter, but I hope that's something they rectify."

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