Bad blood between two men led to one stabbing the other in Blackpool town centre, a court heard.
Derek Buchanan caused a puncture wound to his victim’s chest after stabbing him with a key or key ring.
Buchanan, 19, of Church Street, Blackpool, had pleaded guilty to an offence of unlawful wounding.
Preston Crown Court heard there had been bad blood and ill feeling between the two men and exchanges had taken place between them on Facebook.
They came across each other on Church Street, Blackpool, on September 16.
Initially Buchanan did not want to accept a challenge to fight, but walked away.
The court heard he was pursued by the other man who was said to have become violent, spitting at the defendant and hitting him several times.
Buchanan responded by striking out at him, while holding a key or key ring in his hand.
Hanifa Patel, prosecuting, said the other man walked away, not realising at first that he had been stabbed. He sought medical attention for a small puncture wound to the right centre of his chest and a large elbow gash.
His wounds were cleaned up and stitched.
At the time of the wounding, Buchanan was on licence from a period of detention that had been passed last year for offences including false imprisonment. He was released on licence in July last year.
Rachel Woods, defending, said Buchanan had had a difficult upbringing. Despite his background, he seemed to have been doing well since his release last summer.
She told the court: “Had the other man not come across him that afternoon it is highly unlikely there would have been a further offence.
“The defendant did initially walk away, but after a degree of provocation, lashed out and caused the injuries”.
Miss Woods said Buchanan had acted in excessive self defence. The teenager was given 18 months detention suspended for two years, with two years supervision and 180 hours unpaid work.