Sydney Swans' Barry Hall has apologised to Brent Staker after flooring him with a left hook in what he called a 'mind snap' during Saturday's game at ANZ stadium.
Hall has been charged with striking and faces a lengthy suspension after punching Eagles defender Brent Staker in an apparent moment of madness.
Hall said he was shocked when he watched the replay.
"It was just a reaction sort of thing.
"Certainly, watching the vision afterwards, it looked terrible and as the match review said, it was unacceptable."
The incident came in the 25th minute of the first term as Hall wrestled with Staker behind play.
Hall appeared to suddenly lose patience, turning to deliver a big left hook to Staker's jaw and laying him out for almost three minutes.
Staker took no further part in the match, sitting hunched on the interchange bench even when his teammates approached Hall angrily at quarter time.
He appeared pale and groggy as he wandered around the boundary line, under the supervision of the West Coast doctors.
Swans coach Paul Roos said he didn't see the clash but that Hall is likely to miss several weeks anyway after injuring his wrist late in the last quarter.
"Being down on the bench, I can't get to see the replay.
"But I don't think he'll be playing too much for the next however many weeks anyway. I think he might have broken his wrist."
Hall is believed to have broken his wrist when he ran into an exposed section of the fence.
The Swans, who are fourth on the ladder with a 2-1 record after three rounds, face defending premiers Geelong next week.