The incident is believed to have occurred in the early hours of this morning.
The incident occurred in the early hours of Saturday morning on Tucker Street in Castlebar.
Gardaí received reports of an unconscious man after an alleged assault outside a licensed premises on the street.
A Garda spokesperson has said that the scene was preserved and an examination was carried out.
He was taken to Mayo University Hospital, but has since been moved to Beaumont Hospital in Dublin.
Investigations are ongoing, and the Gardaí are appealing to anyone who may have witnessed the incident to contact them.
“Any road users or persons with camera footage (including dash-cam) in the Tucker Street area between 2:30am and 3:15am are asked to make this footage available to investigating Gardaí,” a statement said.
“Anyone with information is asked to contact Castlebar Garda station on 094 903 8200, the Garda Confidential Line on 1800 666 111, or any Garda Station.”
According to the Irish Mirror, neither of the two the suspects have been arrested, while it is also understood that one of them is a sports star.
