Southend United boss Paul Sturrock has warned midfielder Anthony Grant he will be disciplined for his "stupidity" in Tuesday's 1-0 win over Oxford.
Grant and U's striker Tom Craddock were dismissed following an altercation in the second half of the Johnstone's Paint Trophy regional quarter-final.
"Grant's stupidity changes the game," Sturrock told BBC Essex.
"He put his hands on somebody's face. You can't do that. He will be sternly punished, I can assure you."
Oxford had already suffered a blow in the 12th minute when keeper Wayne Brown was sent off for handling outside the area.
With no substitute shot-stopper on the bench midfielder Asa Hall put on the gloves and was immediately picking Ryan Hall's free-kick out of the net.
But the Shrimpers failed to extend their lead, much to Sturrock's annoyance.
"There wasn't much in the match. The goalkeeper was unlucky. But by the letter of the law he has to go," said the Scot.
"I was really disappointed with the way we played after going 1-0 up.
"Credit to Oxford, they battled really hard. But I was very disappointed my players didn't show a clinical mentality.
"The amount of times I see a makeshift goalie go in who doesn't get tested. It's just an attitude problem from the players.
"Slow build up. Slow passing. Square and back. Never penetrating."