Crystal Palace winger Jason Puncheon has been fined £15,000 by the Football Association and warned about his future conduct for Twitter comments he made in relation to former boss Neil Warnock.
Puncheon took exception to criticism from Warnock about his penalty miss in a 2-0 defeat by Tottenham in January.
Warnock said he would not have trusted Puncheon, 27, to take the penalty.
Puncheon retaliated with derogatory messages on the social networking platform, which he later deleted.
He said he would accept "banter" and "opinions" over his miss and wrote: "As a man I will live with that, which is fine, but I will not live with [Warnock's] opinion."
The FA found the former Southampton player had "failed to act in the best interests of the game and/or acted in a manner which was improper and/or used abusive and/or insulting words".
Warnock, who made his criticisms of the penalty on radio station Talksport, signed Puncheon on loan for four months from September 2011 when he was manager of QPR.
He said: "There's no way I would've trusted him with a penalty. You've got to have somebody a little bit more cool - and he's not like that, Jason.
"He can whack a 35-yard free-kick in here and there but a penalty, with all the pressure on him at a place like White Hart Lane... not in a million years for me."