Coming down from Scotts Road on their motorcycle at 1.20am yesterday, dance teacher Shan Gomes and her husband Kun Wai Kit saw a wet patch on Paterson Road in the distance.
It looked a lot like a puddle of water.
But when they rode over the area on their Honda Phantom motorcycle, they realised that it was oil, because their bike suddenly started swerving.
"I told my husband to slow down. We were not going fast so he put his foot down to try and stop the bike, but we still slipped," said Ms Gomes, 30. "The bike crashed and skidded across the road."
The stinking black oil, smelling like a mixture of diesel and sewage, clung to their clothes and bodies as they slid over the asphalt, she added.
"My husband's arm was all black and bloody," she said, adding that she sprained her wrist in the fall.
The couple tried to get up, but it was difficult even though they were wearing rubber sneakers. It was almost impossible to walk on the greasy road, said Ms Gomes.
The couple are believed to be among the first motorists on the scene of the Paterson Road oil spill. Riding towards the junction, they had noticed a lone worker standing beside a small, unmarked tanker truck parked kerbside, hosing down a section of Paterson Road.
They slowed down, but still crashed.
"It was so dangerous, we saw five or six taxis going by and, when they stopped, you could hear them screeching," said Ms Gomes.
The couple saw a passing police car and alerted it to the danger and also called the police at about 1.30am, about the same time that police said they were notified.
"The police officers got the worker to put out a sign but it was so small and inadequate," said Ms Gomes.
For the next half-hour, the couple stood by the road waving to oncoming motorcyclists. They left only at about 2am when a Land Transport Authority (LTA) officer arrived.
They had to clean the oil off their motorcycle with wet wipes before they could ride home.
"We were very lucky we spotted the oil patch from a distance and slowed down. If we weren't conscious of that, (our injuries) could have been a lot worse."