Hours later, Cow Lane had been cordoned off with a police patrol car blocking off the Camp St entrance.
At the time, Sergeant Steve Watt said Queenstown police were called to an assault in the lane at 3.20am, sparked by an altercation between two pairs of men in a Camp St bar.
All four were kicked out of the bar.
Wijenayake, who's since watched the CCTV footage, says he's seen hugging one of the other men before both pairs "split".
About 20 minutes later the alleged offender came across Wijenayake outside another bar in the lane.
He tried to confront the Sri Lankan national, but Wijenayake says he can be seen pushing him away.
Next, a single, king hit-style punch is directed at Wijenayake's head.
He was standing close to a wall near the entrance to Stratton House.
After being hit, he stumbled, head-first, into the wall, then "zig-zagged" into the middle of Cow Lane, where he collapsed.
An ambulance took him to Lakes District Hospital before he was flown to Dunedin Hospital in a critical condition with a fractured skull.
He spent four weeks in a coma in intensive care and underwent a craniotomy, where part of his skull was removed to relieve pressure from brain swelling.
Another surgery followed about three-and a-half months after he came out of the coma, in which the plates were inserted, and the bone flap was replaced.
After that he was taken to rehab — he doesn't even remember going there, nor does he remember his parents arriving from Sri Lanka to be by his bedside.
Initially, he didn't even recognise them.
Meantime, his wife was in his home country, pregnant with their first child, and unable to get to New Zealand to be with him.
"By the time I was out [of hospital], my baby was just about to be born.
"I couldn't go for the delivery because of the medical restrictions — I was asked not to drive and not to fly for six months, so I couldn't be there for my wife."
Little Yathula arrived on October 25, 2019 — Wijenayake's medical restrictions ended on November 15 and he left New Zealand the same day.
He's since spent just one precious month with his wife, a nurse, and son.
'I'll end up nowhere'
Wijenayake is now 35, and the wider effects on his life from that single punch are devastating.
He moved to NZ almost a decade ago, first living in Auckland where he studied hospitality management and professional cookery, with a goal of becoming a chef and gaining NZ residency.
He worked in a bakery there before being offered a position as a chef at Lone Star in Queenstown.
He passed his international English language testing system (IELTS) assessment, to reach the required number of points to be eligible for residency, after which he had two years to submit his application.
But, between times, Immigration NZ moved the goal posts, and brought in increased salary requirements, of $25.50 an hour.
"I had to look for jobs where I could gain that amount of money — $25.50 is not easy in this country, it's very hard to find, especially as a chef."
He managed to find one, at Pub on Wharf, which then agreed to help sponsor him through the residency process.
He'd been there just over three months when he was attacked.
By the time he came out of hospital, six months later, his IELTS assessment had expired, meaning he couldn't use it towards his residency.
Along with the physical and cognitive effects of his brain injury, perhaps unsurprisingly, his mental health has also taken a beating.
While Wijenayake counts himself lucky to be alive, the impact of one person's decision in one moment will have lifelong effects for him and his family.
"I've spent nearly a decade in this country and I'll end up nowhere.
"It's destroyed all my dreams and all my plans."
Meantime, at the end of last year after a jury trial in the Invercargill District Court, his alleged attacker was found not guilty of injuring him by an unlawful act.
According to the Crimes Act, that charge applies to anyone who injures another person in circumstances that if death had been caused they would have been guilty of manslaughter — the maximum sentence is three years in prison.
Wijenayake has never heard from the man who allegedly attacked him, but has a simple message for him, and others.
"Some people can't tolerate alcohol.
"If you're getting aggressive after drinking, don't drink.
"Please."
'It's heartbreaking'
Local MP Joseph Mooney says he's looking into Sapumal Wijenayake's case.
Mooney, formerly a criminal defence lawyer, says he's working on finding out what the 35-year-old's current situation is, where he fits into the Immigration New Zealand residency application process and what can be done to help him.
"It is a heartbreaking situation — through no fault of his own.
"At this stage I need more information about where he's at so I can find out what can be done."