The incident took place on the man’s driveway in The Avenue.
A police spokesman said:”At around 8.30pm on Monday January 21, two men threatened him with a knife and hit him on the head with a hammer.
The victim – who is in his 50s – required hospital treatment.
The offenders fled on foot with a Konig brand watch which has a chrome front and black strap, as well as a pair of glasses.
One of the robbers is described as mixed race, of medium build and dressed in all black clothing.”
Anyone who has any information about the robbery should call police on 0161 856 7530 quoting incident number 1990 of 21 January 2019.
Details can also be passed on anonymously to the independent charity Crimestoppers on 0800 555 111.