A 20-year-old man was assaulted by a suspect who was carrying an open umbrella.
The victim was assaulted in Woodhouse Lane, near to the junction with Rossington Street, shortly after 2am on Sunday.
He had been on a night out with two female friends when he was attacked after he exchanged words with the man carrying an umbrella.
He was punched once in the face causing him to fall and bang his head leaving him unconscious.
He was taken to Leeds General Infirmary for emergency treatment. His injuries were found to be serious but not life threatening and he was kept in for observations.
The man who punched him was described as white, aged in his early twenties, 5ft 6in to 5ft 8in tall, with short, blond hair which was spikey on top. He was wearing a short-sleeved polo shirt and blue jeans and was carrying a blue/green-coloured umbrella, which he had open despite it not raining. He ran off towards Albion Street.
Anyone who witnessed the incident or knows the identity of the suspect is asked to contact City & Holbeck CID via the non-emergency number 101 or call Crimestoppers anonymously on 0800 555 111.