The 40-year-old had just come out Chillies takeaway on Lanark High Street when the suspect came up and attacked him with the pole just before midnight on Saturday.
The suspect then left the scene.
Emergency services were called and the victim was taken by ambulance to Wishaw General Hospital for treatment to serious head injuries.
Police are appealing for information about the incident in the South Lanarkshire town.
The suspect is described as 5ft 11, of skinny build, clean shaven and with short dark hair.
He was wearing a black tracksuit with a motif design.
Detective Constable Gerry Hattie, from Wishaw CID, said: “This was a targeted and brutal assault on the victim, who has been left in a serious condition is hospital.
“I would appeal to anyone who was in the vicinity of Lanark High Street around midnight and may have witnessed what happened, or noticed a man matching the above description, to please get in touch.”