The man was stabbed at around 1am on Sunday on the car park of the The Perry Hill Tavern on Perry Hill Road in Oldbury.
He went on to seek refuge inside the pub where staff called an ambulance for him, though the venue says the incident has nothing to do with them.
A second man involved with the incident also suffered injuries, but neither are thought to be life-threatening.
All five men were arrested on suspicion of wounding.
West Midlands Police say four of them have now been released under investigation, with the fifth man being released without charge.
A police spokesman said: "Four men aged 21, 22, 25 and 33 have been released under investigation as enquiries continue into a stabbing on Perry Hill Road, Oldbury on Sunday.
"A 21-year-old man suffered injuries which were thankfully not life threatening.
"A 30-year-old man who we also arrested was released without charge."
Anyone with information or mobile phone footage has been asked to get in touch via live chat at west-midlands.police.uk quoting crime number 20/608532/22.