Arrest after Sydney man stabbed in face

A 50-year-old man has been taken to hospital after suffering a 10-centimetre-long stab wound to the face during what's believed to have been a domestic-related incident in Sydney's west.

The man allegedly became involved in an argument with a 21-year-old man outside a home in Auburn on Tuesday afternoon, during which he was stabbed in the cheek, police say.

Both went inside the home, where the younger man allegedly attacked the older man again, giving him another cut to the head.

The 21-year-old man has been admitted to a mental health facility for assessment and is expected to be charged over the incident.