A chess boxing match ended in chaos when the timekeeper allegedly laid out the referee in a row over when to ring the bell.
Timekeeper Andrew 'The Rock' Costello, a former Exeter policeman, was so angry when the chess referee did not stop the game at the bell that he went round the ring and allegedly knocked him out with a single punch.
Chess player Rajko Vujatovic was refereeing the chess part of the tournament and was left with a broken jaw which prevented him eating solid food for ten weeks, Exeter Crown Court was told.
The violence broke out at a chess boxing event at the Club Rococo in Exeter at which contestants sandwich three minute rounds of chess with three minute bouts of boxing.
The jury have been shown CCTV of the even which shows Mr Vujatovic leaving the ring and going just out of picture moments before the alleged attack.
He is seen falling next to the ring and being attended by the paramedics who were on standby to treat the boxers in the event of then being injured during the contest.
Costello, aged 47, of Mount Pleasant, Exeter, who is a champion chess boxer, denies causing grievous bodily harm and the lesser alternative of causing actual bodily harm. He says he was acting in self defence.
Miss Bathsheba Cassel, prosecuting, said Costello organised the Sunday afternoon event at the club last August and invited Mr Vujatovic to referee the chess match.
Costello acted as timekeeper and a dispute arose over timings because he rang the bell to finish a round of chess 30 seconds early but Mr Vujatovic chose to follow the chess clock and allowed it to continue.
She said the victim went up to Mr Costello to explain why he had let the game continue and was knocked out by a single punch. He suffered a broken jaw which had to be pinned in an operation.
Mr Vujatovic said he agreed to come to Exeter from his home in London to referee the chess part of the event as a favour to Costello and the atmosphere had been good until the dispute over timing.
He said he had never been a boxer and was 'half the size' of Costello and his involvement in the sport was as a chess expert and coach.
He said he let the chess round carry on after Costello signaled it to stop because he was going by the chess clocks used by the players.
He said:"When I left the ring I stood in a small area back stage and waited for the crew to take the board and the table, chess set and clock out of the ring and get it ready for the next round of boxing.
"Costello was not in the immediate area. He walked over to me so he was on my right. I said very gently that I had let the round run on. I presumed he had made a mistake.
"After speaking to him we were stood side by side and I turned to look at the people getting the equipment out of the ring.
"The next thing I knew my legs turned to jelly and I was unconscious before I hit the ground. Then I was aware of having an oxygen mask on and paramedics all around me."
He said Costello phoned him two days later to apologise and told him he hit him because he was under stress at the time.
Mr Vujatovic said:"He told me it was only a light tap and he could have caused me a very serious damage. He said with a bit of smugness it was a deliberate punch to the chin to what he called a knockout point.
"I said hitting me was like hitting a girl because I was half his size."
