Motherwell have confirmed that captain Paul Quinn suffered a broken jaw during an incident in his home town.
The 22-year-old will undergo surgery on Monday and could miss the rest of the season.
Motherwell claim the player had been assaulted in Wishaw at the weekend.
A spokesman said: "Motherwell Football Club can confirm that club captain Paul Quinn was attacked at Baker Street nightclub on Saturday night and was taken to Wishaw General Hospital.
"For legal reasons, the club cannot comment any further as the matter is now in the hands of the police.
"We wish Paul a speedy recovery from his injuries."
Strathclyde Police said that a man had been arrested over an incident in the club but had no record of Quinn being involved.
A police spokeswoman said: "A 39-year-old man was arrested in connection with an incident in Baker Street nightclub. A report will be sent to the procurator fiscal."
The news is a blow for Well boss Mark McGhee as his side look to secure their European football next season by finishing in third place.