Following a night out, the 28-year-old man was on his phone at about 12.40am on Saturday when he was assaulted from behind.
He fell to the ground and momentarily lost consciousness. When he came round, he realised his phone and wallet had been stolen.
He suffered a broken nose and a fractured cheek bone as a result of the attack. Although the victim did not see who attacked him, he believes it was two men.
Police are keen to hear from anyone who was in the Cadbury Heath Road area on Saturday between 12.30am and 1am and might have information on this robbery.
Contact 101 and quote reference number GR108221/14.