Gang member Muhammad Nazmir Osman and his friends attacked two men who had looked at their group during an argument.
It set in motion a night of violence in 2015, that would end with the death of American stuntman John Denley Nelson, 30.
Nazmir, 24, who threw the first punch, was jailed yesterday for 4½ years with 12 strokes of the cane, after pleading guilty to rioting and to unrelated charges involving unlicensed moneylending and being in possession of two parangs.
He was also fined $30,000.
Three of his accomplices were also convicted of rioting yesterday.
Muhamad Adnan Abdullah, 24, and Masazlie Mohamed Salleh, 43, were each jailed for 2½ years and given six strokes of the cane.
The fourth man, Ahmad Jumaidi Salleh, 24, was jailed for 1½ years.
The rampage started outside Beer Inn in Circular Road, after Nazmir, Ahmad and Adnan joined Muhammad Haziq Hashim, 24, and Norazilah Zainol, 23, for drinks at 2.40am on Dec 24, 2015.
Two friends, Mr Desmond Pheh Hou Chin, 22 and Mr Teo Zhihan, 29, looked at the group while members of the group were arguing.
Nazmir confronted the pair and punched Mr Pheh's face. Several members of Nazmir's group then joined in and attacked the two men.
When another onlooker, Mr Akash Kukreja, 31, went over to check on Norazilah, the group turned on him.
A woman, Ms Charlotte Roscoe, 26, tried to help Mr Kukreja and was also beaten up.
At around 3am, Masazlie and Adnan got into a fresh dispute with a woman in Circular Road.
When Mr Nelson - who was not involved in the earlier scuffles - tried to mediate, one of the attackers punched him.
He fell, hitting his head on a kerb, and died of a severe head injury just over a week later.
Two of the attackers were convicted in court last year.
Muhammad Izzuandy Yusof, 24, was sentenced to 2½ years' jail with six strokes of the cane.
Muhammad Saiful Rizal Mohamed Hanifa, 26, was jailed for 28 months and ordered to get six strokes of the cane.
The cases of nine others, including Haziq and Norazilah, are still pending.
The maximum sentence for rioting is seven years' jail and caning.