The slashing took place at about 2.30pm, at the junction of Sims Avenue and Aljunied Road.
The victim, a 29-year-old man, suffered slash wounds on his left arm after he was attacked from behind by a knife-wielding man.
He was earlier seen quarrelling with the victim at the road junction.
The victim was sent to Tan Tock Seng hospital, while police arrested the attacker the same day.
The case is being investigated.