An ugly brawl that blew up at a busy intersection in Sydney's west during peak hour on Tuesday has been described as a road rage attack.

The fight involving four men erupted on the corner of Centenary Drive and Douglas Street in Merrylands about 5pm.

A driver filmed the altercation, which was shared on social media.

A NSW Police spokeswoman said no formal complaint had been made but the footage was being reviewed and an investigation was under way.