A man suffered a fractured eye socket when he was assaulted before the Grand National race at Aintree.
Merseyside Police issued an appeal for witnesses following the attack at Aintree Racecourse on Saturday.
A spokesman said the victim was assaulted by another man at about 5.10pm, shortly before the world-famous steeplechase was about to start.
The incident happened close to the front rail, near the Lord Daresbury & Princess Royal Stand, on the racecourse side.
Detective Inspector Gary Stratton said: “Despite the good nature of the vast majority of racegoers it is disappointing to see that an incident such as this occurred, with a man suffering a serious injury as a result.
“We are carrying out a number of inquiries and are particularly keen to speak to a man described as a white male with blond hair, wearing a beige jumper and a checked shirt.
“We believe he may have vital information to assist our investigation and would ask him, or anyone who recognises the description, to please get in touch.”
Anyone with information is asked to contact @MerPolCC or call 101 quoting reference 19100160830.