St George police are investigating a stabbing at Arncliffe on Sunday.
Just before 12pm emergency services were called to Stewart Street after reports of a stabbing.
A man in his 20s was treated by paramedics for a chest wound.
He was taken to St George Hospital in a serious condition.
An investigation has been launched with police urging any witnesses to come forward after an earlier incident involving a group of men at Wollongong Road.
Anyone with information is urged to contact Kogarah police or Crime Stoppers on 1800 333 000.