She was returning to her ninth-storey flat in Bukit Panjang at about 3am when the lift stopped on the eighth storey.
When the door opened, Miss Yati (not her real name) saw her ex-boyfriend.
She was surprised to see him, but was not worried as they were still on friendly terms, or so she thought.
He got into the lift and they hugged and kissed. They continued their smooching after stepping out of the lift on the 10th storey.
After some time, she said she wanted to go home. To her shock, her ex took out a kitchen knife and stabbed her twice in the chest.
He then slashed off the tip of her right thumb before kicking her in the stomach.
He fled and threw the weapon into a rubbish bin at the void deck. It was never recovered.
On Tuesday, technician Muhammad Idham Johari, 28, was jailed for eight years and given 12 strokes of the cane after pleading guilty to voluntarily hurting Miss Yati, possessing a foldable knife, and two drug-related offences.
A second assault charge involving her and two other drug-related charges were taken into consideration during sentencing.
Miss Yati, 25, told The New Paper that she still does not know why he had attacked her on July 25 last year as they were not quarrelling at the time.
Asked why she had smooched him that night, she said it was because they were still on "friendly terms".
Miss Yati's eldest sister, who wanted to be known only as Madam Siti, 33, related most of what happened that night as Miss Yati still finds it difficult to talk about the incident.
She said the attack occurred when Miss Yati was on her way home after a karaoke session with her friends. One of their brothers was watching television when he heard a commotion.
He shrugged it off at first, assuming their neighbours were having a domestic dispute.
"My brother only realised it was (Miss Yati) when he heard somebody screaming, 'Kakak!' (elder sister in Malay) and recognised her voice," said Madam Siti, a housewife who has four children between one and 14 years old.
Her brother, 30, flung open the front door and saw Miss Yati in the corridor, covered in blood. By then, Muhammad Idham had fled.
He ran to Madam Siti's bedroom and woke her up.
She recounted: "I didn't know what was going on at first and scolded him. I asked him, 'Why are you waking me up at this ungodly hour?'
"But the anger turned to panic when he told me what happened. I ran to the corridor."