Up to 10 people were involved in the "brutal" assault in Rutherglen, South Lanarkshire, on Tuesday.
The victim is being treated for serious injuries at the Victoria Infirmary in Glasgow.
Officers have appealed for witnesses to the attack which took place at about 5.30pm in Lochiel Lane.
Detective Sergeant Susie Cairns said: "At this time we believe that there were at least six but possibly up to ten people involved in the attack on this man.
"Whether it was a targeted attack or not has still to be established.
"We have been checking local CCTV and carrying out door-to-door enquiries to establish exactly what happened."