A Hamilton dairy worker chased a masked man wielding a hammer out of the store this morning when he tried to rob the store.
The suspect, wearing a black mask and holding a hammer, went into the Edinburgh Superette in Hillcrest at 8.25am.
Two workers were in the store when the man demanded money, but instead of following orders one of the workers gave chase.
Detective Senior Sergeant Mark Greene said one of the shop workers who chased the teen outside suffered minor injuries when he fell over.
The masked man, described as wearing a red T-shirt and black shorts, managed to get away. He was last seen on Knighton Rd.
Police carried out a scene examination this morning and were making inquiries which included looking at CCTV footage.
It is the second time in just over a week the dairy has been targeted.
The dairy was also robbed on Wednesday September 13 by two masked robbers who also entered the store in broad daylight and stole cash and cigarettes.