The incident is believed to have occurred between around 6.15am and 6.30am this morning (Thursday) at the rear of The Plough Business Hub in Church Street, Gainsborough, which was formerly The Plough pub.
Officers are appealing for anyone who might have been in the area at the time and seen or heard anything regarding the incident to get in touch.
They are also interested in information relating to a man seen around the area at the time who is described as a white male, around 6ft in height, well-built, and wearing a dark jacket and knee-length shorts.
The injured man has been taken to Lincoln County Hospital for treatment. His injuries are not thought to be life-threatening or life-changing.
Anyone with any information is asked to contact Det Serg Dave Harrop at Lincs Police on 101, quoting incident number 47 of 24th April 2014 or alternatively contact Crimestoppers anonymously on 0800 555 111.