A 16-year-old boy who stabbed a 14-year-old outside a community centre has been found guilty of wounding with intent to cause grievous bodily harm.
His victim was injured outside the centre in Truro, Cornwall, during the attack on 27 September 2017, suffering a collapsed lung.
The boy, who cannot be named for legal reasons, had already admitted wounding at Truro Crown Court.
He was remanded in custody and is due to be sentenced next month.
The court heard the victim had been at the centre with friends and had gone outside when the attacker appeared, masked and in dark clothes.
He was hit in the side of the head and stabbed in the back during a fight.
Weapon not recovered
He was taken to hospital with with potentially life-threatening injuries, including a collapsed lung, before he later recovered.
The attacker told the court he had "completely forgot I had a knife in my hand" during the fight and had been using it to "strengthen his hand".
He added that the small blade of the knife was already out when he had it in his pocket but that he "wouldn't want to stab anyone".
However, the court earlier heard that he had previously claimed he had carried out the attack because he believed the victim had sexually assaulted a friend.
It also heard he admitted the stabbing on Facebook, to a social worker and a family friend. He also said he had disposed of the knife in a garden.
The knife has never been recovered.