A manhunt has been launched in south-west Sydney today over the stabbing of a teenager who was left seriously injured.

Emergency services were called at 12.20am to Sir Joseph Banks Street in Bankstown, over reports a man had been stabbed.

Police found a 19-year-old man had been stabbed on Waterloo Road, Greenacre, before being taken to Bankstown in a car by friends, where they called triple-zero.

Paramedics treated the victim for stab wounds to the back and leg.

He was then taken to Liverpool Hospital in a stable condition.

Police set up a crime scene and launched an investigation.

Anyone with information or who may have dashcam vision from the two locations should call Bankstown police or Crime Stoppers on 1800 333 000.