An 18-year-old has gone on trial accused of stabbing another teenager seven times in a laneway off Grafton Street in Dublin last year.
Tadhg Costello, of Richmond Hill, Monkstown, is charged with the attempted murder of Josh Leahy from Ranelagh, at Johnson's Court in Dublin city on May 31, 2012.
Josh Leahy told the jury he required surgery for a punctured lung after he was jumped on, thrown up against a wall and stabbed in the back in a laneway last year.
CCTV footage of the incident shows an altercation between a number of young men just before 3am opposite Powerscourt Shopping Centre.
The 18-year-old has given evidence he was in the Lost Society nightclub on South William Street with friends earlier that night.
He said when they left at around 2.30am there was a group of eight to ten young men staring at them.
He recognised one of the men because he was going out with his ex-girlfriend. He said words were exchanged between the groups.
Tadhg Costello denies attempted murder, assault causing harm and possession of a knife.