JACK Stevens was headbutted as Oxford United and Sunderland players clashed during a half-time fracas, according to Karl Robinson.

Words were exchanged between both benches either side of the break at the Stadium of Light, leaving U's staff and players visibly angered.

It remained a bad-tempered second half, with Mark Sykes sent off on the hour mark and Robinson himself dismissed for protesting Sunderland's controversial 81st-minute second goal as the hosts won 3-1.

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The head coach revealed the initial reason for the U's fury was an alleged headbutt on his goalkeeper in the tunnel, which he said was missed by referee Trevor Kettle and his officials.

Robinson said at full-time: “We’re waiting for the police to come. My goalkeeper was head-butted at half-time.

"It’s not right of me to give names.

"There will obviously be an investigation by the FA and they’ll want to bring my players and staff into it."

He added: “There was a bit of a melee.

"Something was said and Jack’s walked behind somebody, he’s just turned around, grabbed him and head-butted him.

“We’ll be waiting to see where this goes from here legally."

The sides went in 1-1 at half-time, with James Henry's opener cancelled out by Lynden Gooch's stoppage-time finish.

But United were reduced to ten men when Sykes received a second yellow card for sliding in on Luke O'Nien as he tried to keep an attack alive.

Robinson said: “That’s a second booking, but he’s tried to win the ball.

"No Oxford fan would criticise him for throwing his body to try and get something out of it.

"I’m proud of how my players fought for each other, afterwards and at half-time.”

The U's held out until the closing stages, when a quickly-taken free-kick found its way to Gooch and then McGeady, who curled home.

The set-piece was given away by Cameron Brannagan, who remained on the floor as play restarted, and United were incensed that Kettle let Sunderland continue.

Robinson said: "I got sent off for saying 'that was a bleeping disgrace and you need to do your bleeping job'."

"Cameron Brannagan’s on the floor and he only got up because he had to.

"He’s struggling because of the tackle and they score.”

There was further controversy late on, when Max Power sealed victory and celebrated in front of the U's dugout.