A mechanic was punched in the face by thieves as he arrived at work on Friday January 10 at 6am.
As he got to Ilkeston Auto Centre on Awsworth Road, two men were stealing a large amount of cash.
He tried to stop them and was assaulted.
Police are appealing for witnesses.
Anyone with information is asked to contact DC Gareth Jones using the non-emergency number 101 or speak anonymously to Crimestoppers on 0800 555111.