Prosecutors have told the Adelaide Magistrates Court that a teenager charged with the murder of Christopher Hatzis allegedly was heard boasting about the attack.
The court heard Mr Hatzis, 19, was stabbed 15 times during a brawl involving up to eight people in Light Square in the city in August.
Another 19-year-old, Dario Stakaj, was arrested this week and is the fifth person charged with murder over the death.
Prosecutors told the court Stakaj allegedly was seen on security footage running from the scene and witnesses allegedly heard him boasting about the attack.
The court was told Stakaj allegedly was heard saying "He's f***ed, that c**t is dead".
Stakaj's lawyer said his client was a soccer star who had been offered a posting in the United States.
Defence lawyer Michael Waye said the allegations were denied.
"The allegations are totally denied with respect to any involvement in the stabbing," he told the hearing.
"The evidence is flimsy at best, there is no direct evidence to suggest he was involved ... there's absolutely nothing, it's a weak case."
Mr Waye said the teenager would miss out on sports opportunities if he were kept in custody, but Magistrate Bob Harrap said the accused's soccer abilities were irrelevant to bail considerations.
He refused bail and adjourned the case until April.