They had known each other for years but that did not stop Lek Lai Seng, now 54, from hitting a woman in the face with a drinking glass.
She is now permanently scarred and has trouble controlling her drooling.
Yesterday, Lek was sentenced to 15 months' jail for causing grievous hurt to Ms Tan Mei Ji, 37, at the Shanghai Dolly Club in River Valley Road at around 2.30am on June 14, 2014.
He was found guilty earlier by District Judge Michelle Yap, after a trial last year on Dec 27.
Deputy Public Prosecutor Tan Wee Hao said in his submissions that the regulars at the nightspot had known each other since before 2010, but Lek and Ms Tan had a feud over money.
Lek had given Ms Tan $60,000 for a business venture that did not materialise.
On June 13, 2014, Ms Tan was drinking at Shanghai Dolly at around 11pm when Lek, who was nearby, gestured to her to walk over to him.
DPP Tan said: "The accused asked the victim when she was going to transfer the money she owed him. She replied that she had already transferred the money to him, and had sent him a message informing him of the same."
This angered Lek as he felt she was arrogant. He splashed a drink on her face and slapped her.
He then swung a drinking glass that he was holding towards the left side of her face, resulting in her bleeding profusely.
CCTV footage showed her staggering backwards, clutching her cheek.
Despite her injury, Ms Tan tried to retaliate by grabbing adrinking glass from a nearby table, but was stopped by club bouncers.
She was taken to Singapore General Hospital and told she needed stitches.
Dr Chia Hui Ling, who treated Ms Tan, later testified in court that she had nightmares and flashbacks of the incident.
Lek, who was represented by lawyer Lim Kia Tong, claimed Ms Tan's injuries could have been self-inflicted.
But Dr Chia testified this was unlikely as she would have had cuts in her hand.
However, she had no such wound.
Lek, who is now represented by lawyer Kertar Singh, will be appealing against his conviction. He is out on bail of $40,000.
For causing grievous hurt, he could have been jailed up to 10 years and fined. He cannot be caned as he is above 50 years old.