It was a big talking point in last night's wonderfully bad Premier League tie between Manchester United and Arsenal at Old Trafford.
Alexandre Lacazette acted quickly when David de Gea was about to take a goal kick, heading the ball out of his palm in the 88th minute.
He went on to stroke the ball into the net and celebrate, but it was ruled out.
Many suggested it shouldn't have been disallowed, with some comparing the goal to when Gary Crosby's headed the ball out of goalkeeper Andy Dibble's hand before rolling the ball into an empty net back in the 90's.
But it turns out the rules have changed since then. Following the full-time whistle, former referee Phil Dowd confirmed Andre Marriner got the call spot on.
"The law has changed, I don't know when. He is considered to be in control of the ball when he has it in both hands, one hand, his outstretched hand or between any other surface." he told BT Sport.
"He has the ball in his hand, he is in control at all time and cannot be challenged. Therefore the foul was given."
In addition, the rule book states:
"A goalkeeper is considered to be in control of the when: the ball is between the hands or between the hand and any surface (e.g. ground, own body) or by touching it with any part of the hands or arms except if the ball rebounds from the goalkeeper or the goalkeeper has made a save holding the ball in the outstretched open hand."
"A goalkeeper cannot be challenged by an opponent when in control of the ball with the hands."
So there we have it. Andre Marriner called it correctly, but you've got to admit, it was quick thinking from substitute Alexandre Lacazette.
Thoughts on last night's game?
Let us know in the comments.