The incident took place near a pizza shop on Sandringham Road around 9pm.
A large group had congregated in the area before a fight broke out.
A 23 year-old man was knocked unconscious, possibly with a baseball bat, and was taken to Bassetlaw General Hospital where he is a serious but stable condition.
If you saw the incident or have any information contact police on 101, quoting incident number 000285-16032014, or Crimestoppers anonymously on 0800 555111.