Police were called to Scampton Way at just before 10.45pm on March 27 where they found a man in his 20s with serious injuries as a result of an assault.
He was taken to hospital but officers confirmed today that the man, named as 25-year-old Jordan O'Brien, has died.
Lincolnshire Police said: "We are now treating this incident as a murder investigation."
Two men, aged 21 and 22, have been arrested in connection with the incident.
Anyone with any information is asked to contact police on 101, quoting Incident 436 of March 27.
Alternatively, contact Crimestoppers, anonymously, on 0800 555 111.