Robbers armed with metal poles stole cash and cigarettes in a '60 second' store raid.
Detectives in Whitefield, Bury, are hunting three men in connection with the attack.
Police said the shopkeeper was threatened and forced to open the till.
He was also ordered to hand over his mobile phone, but escaped unhurt.
The raid happened at Victoria News on Victoria Lane, Whitefield, at around 11.40am on November 20.
Details have only just been released by Greater Manchester Police.
No descriptions have been issued of the men involved.
Detectives said all three entered the store before one walked behind the till and stole cigarettes.
The other two, who were both armed with metal poles, threatened the shop keeper and forced him to open the till.
The force said in a statement on Saturday: "One of the offenders then walked around the till area whilst another jumped onto the counter and forced the shop keeper to hand over his phone before he threw it to the floor.
"The three then made off from the store 60 seconds later on foot towards Charles Street."
Detective Constable Craig Ryder, from Bury CID, issued an appeal for anyone with information to come forward.
A 'number of lines of enquiry' are being followed, he said.
"Thankfully no one was injured during this robbery but the member of staff has been left understandably shaken up," the detective said.
"A number of lines of enquiry have already been followed up and we're now appealing for members of the public to come forward with any information that may be able to assist."
Victoria Lane is off the A56 Bury New Road.
Anyone with information should call police on 0161 856 8158 quoting log reference number 1043 of 10/11/2020, or Crimestoppers anonymously on 0800 555 111.
