He had just completed a food delivery and was riding back to Jurong Point when he noticed a commotion around a tipped lorry at the junction of Jalan Boon Lay and Boon Lay Way.
As he approached on his e-scooter, he realised that the driver was trapped inside and people at the scene seemed unsure of what to do. Traffic that Aug 10 morning was flowing as usual.
Noticing some fuel that had spilled onto the road, Mr Muhammad Riau Alfian's first thought was to get the driver and everyone away from the area in case there was a fire or an explosion.
The 28-year-old GrabFood delivery rider leapt into action, his instincts from his time as an auxiliary police officer kicking in.
Setting aside his e-scooter, he climbed on top of the truck and tried to open the door from the passenger's side, but found it stuck.
He then spoke to the trapped driver, who looked to be in his 70s, telling him he would break the window to rescue him.
Using a crowbar another passer-by had obtained from a nearby construction site, Mr Riau managed to break the window and pull the man out of the lorry.
"When I saw there was a spillage from the fuel tank, I was not concerned about my safety but the safety of the others. I did not want any more casualties," Mr Riau told The Straits Times in an interview at his home in Boon Lay, where he lives with his sister and her family.
"After I managed to take (the driver) to safety, I was very relieved because he did not seem injured, just traumatised."
Mr Riau left the scene as soon as paramedics and rescue workers arrived to get back to work. The driver was taken to hospital.
Mr Riau's heroic efforts were captured on video by a Facebook user, and the clip made its rounds, earning him praise from the many netizens who saw it.
Describing himself as shy and unused to publicity, Mr Riau, who is one of three siblings, had no idea he was famous until his sister told him.
"Honestly, I don't feel that what I did was very heroic because I was just doing what I could to help," he added.
The trapped driver's family contacted him after the incident. Thanking him, they told him the driver was fine.
This was not the last time Mr Riau would stop to help a stranger.
Earlier this month, he stopped to attend to a motorcyclist who had injured his right shoulder, rendering first aid to him, Mr Riau, who is not married but is in a relationship, told The Straits Times.
"I would like to see more Singaporeans help one another because this is what we can do to build a stronger society.
"During the National Day Parade, we always sing 'one people, one nation, one Singapore'.
"It takes each and every Singaporean to build a better Singapore," said Mr Riau.