The victim was approached by another man in Worcester Street and struck with a tennis racket and repeatedly kicked in the head when he dropped to the floor.
A 25-year-old man was arrested on suspicion of assault at a nearby address and has since been bailed with conditions.
The incident happened sometime between 11.30pm on Sunday and 12.30am on Monday.
Inquiries continue and anyone with information is asked to contact police via Live Chat at west-midlands.police.uk between 8am and midnight, or call 101 anytime.
To remain anonymous call Crimestoppers on 0800 555 111. Quote crime reference 20DY/236851K/19.