A dad bit off a love-rival's finger in an attack that saw him 'spit blood out like an animal' at his child's nativity play.
Lee Wilkinson attacked Michael Dent as they waited for the performance to start at Harton Primary School in Tyne and Wear last December.
Fortunately, children were getting changed in a room elsewhere so didn't witness the attack.
At Newcastle Crown Court Wilkinson, from South Shields, pleaded guilty to unlawful wounding and a separate public order offence relating to a run-in between the two men last Christmas Eve.
The judge told him it was likely he will go to jail.
Both Mr Dent and Wilkinson had been waiting to watch their children perform at the nativity.
One witness said: "The two men started to fight in front of all the parents.
"One bit the finger off the other and spat the blood out like a animal."
One mum said: "I can't believe that it happened - a school is not the time or place to be fighting.
"You can understand children fighting in the playground, but not parents."
Another witness said: "It was horrendous. Everyone seems to think that no kids saw what happened, but I was there with my two-year-old little girl right in front of it. It was disgusting and she should never have seen such a thing.
"He spat out the finger tip with a mouth full of blood and smiled. No concern for anyone. It was a horrific experience and he deserves everything he gets. A school nativity is not the place to start any violence."
Wilkinson had admitted his guilt on a basis, which was not read out or explained in court.
The 40-year-old had been due to be tried on the more serious charge of wounding with intent and affray, which were dropped after he entered his guilty pleas.
Prosecutor Neil Pallister told the court: "There is somewhat of a complex background to the case and indeed it is accepted Mr Dent himself was too cautioned in relation to assaults on the defendant Mr Wilkinson.
"Matters came to a head at the nativity play, approximately a year ago."
At the time of the incident, it was claimed Wilkinson had previously been in a relationship with Dent's former wife. Wilkinson was granted bail until January 25 next year, when he will be sentenced but was warned he may end up behind bars.
Judge Simon Hickey said: "A custodial sentence is almost inevitable for such a serious offence as this, in my judgement."