A 38-YEAR-OLD man was attacked on Henley Bridge during the regatta.
Thames Valley Police are appealing for witnesses following the assault, which happened between 10.30pm and 10.45pm on Friday.
The victim was with his friend, a man aged 44. Officers say the offender started an argument with the 44-year-old and the victim approached the offender.
A spokesman for the force said: The offender then punched the victim who suffered facial injuries, which required hospital treatment.
He is described as a white male, in his mid twenties or early thirties, 6ft 1in or 6ft 2in, of a medium build, with blonde hair and stubble. He was wearing a checked shirt.
The offender was with two females at the time who were also in their mid-twenties to early thirties.
If you witnessed the incident, or have any information which may further the investigation, please contact Det Con Alistair Bagshaw via the 24-hour Police Enquiry Centre on 101.
If you dont want to speak directly to the police you can contact the independent charity Crimestoppers anonymously on 0800 555 111 or online at crimestoppers-uk.org (opens new window). No personal details are taken, information is not traced or recorded and you will not go to court.