The 33-year-old victim was shot in the hip at a house on Normanton Avenue, Weaste, Salford, at about 18:15 BST on Wednesday. His injuries are not thought to be life-threatening.
Police are exploring a possible link to the death of Paul Massey, found dead outside his home on 26 July.
No arrests have been made.
Ch Supt Mary Doyle, of Greater Manchester Police, said: "We are looking into the possibility that this incident is connected with the murder of Paul Massey.
"I believe that the answer to what happened to Paul Massey, and now this incident, lie within the community and I would like to urge anybody with information to come forward."
Police patrols have been increased in the area to prevent further incidents and reassure the public, she added.
Massey died from a gunshot wound to the chest after being shot four times outside his home, about four miles away from the scene of the latest shooting.
Once dubbed "Mr Big", he was jailed in 1999 for 14 years over a stabbing, unsuccessfully stood to be Salford mayor in 2012.
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A new shooting may be linked to the death of a convicted criminal nicknamed "Mr Big" who was gunned down outside his home last month, police have said.