Police are trying to trace people who were in or around Bargain Booze, in South Street, Tarring, when a fight broke out around 9.50pm.
Two men, a 28-year-old and a 33-year-old both from Worthing, have been arrested on suspicion of grievous bodily harm and bailed until June 8.
Detective Constable Tony Taylor said: “There were a number of customers in the shop and also passers who might have witnessed what went on outside the shop. We are particularly keen to trace a couple who might have spoken to the victim before the assault. Anyone with information is asked to contact us on 101 or email [email protected] quoting serial 1457 of 5/4.”