Stoke defender Robert Huth has apologised for the incident in Saturday's match against West Ham when he struck Matthew Upson across the face.
The German was yesterday charged with violent conduct by the Football Association after his swinging arm was missed by referee Martin Atkinson.
Huth and his club have accepted the player's guilt and are awaiting his punishment - likely to be a three-match ban - from the FA.
"Stoke and Robert Huth accept the FA charge of violent conduct and would like to apologise for the incident at the Britannia Stadium on Saturday," said a club statement.
"All players were briefed at the beginning of the season about obstructing opponents at set-plays and Robert reacted in frustration at being impeded by Matthew Upson for the second time in the game, stopping him from marking James Tomkins at set-pieces as instructed.
"Robert Huth's actions are totally out of character for a fully committed defender who has only received one red card - for two cautions - in nearly eight years of playing in the Premier League.
"We await the FA verdict on the incident."