The 36-year-old man and a woman, who is 34, were both attacked outside the Golden Pheasant pub in Auchinloch, North Lanarkshire, early on Saturday morning.
Police Scotland said the man had been seriously assaulted, and is being treated in the Southern General Hospital in Glasgow for facial injuries.
The woman did not require hospital treatment.
Detective Constable John Currie of Coatbridge Police said: "This crime was reported to us last night, and since we received the report officers have been carrying out inquiries to establish more details on the circumstances surrounding the incident and those responsible.
"The 36-year-old man is currently detained at the Southern General Hospital in Glasgow where he is being treated for facial injuries.
"The 34 year-old woman did not require hospital treatment."