A man was knifed in the buttocks following a fight over a car park space in Sydney's west last night.

Police said the 26-year-old got into an argument with a woman over a car park at a Parramatta shopping centre about 8pm.

The man took the park and went inside to do his shopping, while the woman, still outside, called two friends on her mobile phone.

Police allege two men soon arrived at the shopping centre and went inside to find the 26-year-old, challenging him in the food court.

Police said the two men then assaulted the 26-year-old, stabbing him in the buttocks and bashing him.