THE AFL has conceded an umpiring error led to a Brisbane goal being incorrectly disallowed during the Lions' clash with Sydney on Thursday night.

Morris took a mark 30m from goal just before the three-quarter time siren sounded and stepped back off his line to take his set shot as a right foot snap.

Although Morris appeared to kick over the player on the mark, the adjudicating umpire thought otherwise and called play-on, wiping away the goal after the ball sailed between the posts.

In a statement on Friday, the League acknowledged the decision was incorrect, saying Morris had complied with the rule despite remaining short of his line of kick because he had kicked over the player on the mark.

"The umpire standing directly behind the line of kick judged that Logan Morris did not return to the line of kick and therefore called play-on," the statement read.

"On further review, while Morris was short of the line of kick, we believe he has complied with the rule by kicking over the man on the mark and has not improved the angle to the goal posts and therefore play-on should not have been called.

"We are clarifying to umpires and clubs that where a player lines up perpendicular to their line of kick, they must either kick over the player on the mark, or kick from the line of kick."

The overturned goal ultimately had no bearing on the result, with Brisbane cruising to a 43-point win over the Swans.

Speaking post-match, Lions coach Chris Fagan said the decision was confusing and the club would be seeking clarity from the League.

"My understanding of that rule is as long as you start near the boundary and kick over the guy's hands on the mark, that's ok," he said.

"I thought that's what he did. I wasn't standing right there on the spot, but that's what it looked like to me.

"It would be good to get some clarity on it because the learning for Logan might be 'If you ever get another shot on goal and the siren's gone mate, maybe you've just got to go straight back and kick over the hands on the mark so there's no doubt you've done the right thing'.

"From what the explanation is we got earlier in the year, I think he did everything right. What did you guys think?

"We'll ask because he did that thinking he was doing the right thing.

"If he wasn't, we all need to know so we can learn from it. That's ok."

It was reminiscent of Nick Watson's after-the-siren shot against St Kilda in round 12 where the Hawthorn small forward appeared to arc to his right, making his angle worse, having his accurate kick rubbed out.