Mustafa Ya'acob confronted an acquaintance he felt had stared at him, raining punches on him until the victim passed out.
Yesterday, Mustafa, 62, was jailed for six months and fined $7,966.10 after pleading guilty to one count of assault, and four charges involving contraband cigarettes.
Mustafa had seen Mr Alizah Haron, 48, drinking alcohol alone at a coffee shop at Block 26, New Upper Changi Road, at around 10pm on Dec 14, 2016.
The unemployed man, who was there to buy some dinner, accused Mr Alizah of staring at him as he walked past. He then told the younger man to accompany him to the back lane of the eatery for a "talk".
Mr Alizah did as he was told and apologised when confronted, explaining that he was intoxicated.
But Mustafa punched Mr Alizah's face multiple times. He stopped and walked away only when the younger man lost consciousness.
Mr Alizah regained consciousness when someone from the coffee shop splashed water on him. The good Samaritan also accompanied him home. Mr Alizah's wife took him to Changi General Hospital.
She also lodged a police report, the court heard.
A medical report dated Dec 29, 2016, stated that Mr Alizah had suffered injuries which included a fractured nasal bone, a cut on his chin and a bruised chest.
Separately, Mustafa also admitted in court that between August 2016 and October last year, he had in his possession and was dealing with more than 1,000 sticks of contraband cigarettes.
The total amount of duty unpaid was $592.48.
For assaulting Mr Alizah, Mustafa could have been jailed for up to two years and fined up to $5,000.