Former Scotland captain and Rangers assistant manager Gary McAllister has been treated in hospital after he was punched in the face on a night out in Leeds.
McAllister was outside a bar on Call Lane, in the city centre, when a man attacked him at around 4am on Sunday.
West Yorkshire Police are appealing for anyone who saw the attack to get in touch.
Detective Inspector James Entwistle, of Leeds District CID, said: "We are investigating an assault that occurred in Call Lane, in Leeds city centre, at about 4am yesterday.
"The initial report was that a man, aged in his 50s, was stood outside a bar when a man approached him and punched him in the face, causing injuries that required hospital treatment.
"We are currently arranging to speak to the victim to take fuller details of the incident and will be progressing the investigation to identify the person responsible."
It was reported that McAllister was waiting for a taxi with his wife when the attack happened.
McAllister played for Leeds from 1990 to 1996, a period which saw them become champions of the former First Division in 1992. He captained the team for two seasons before a move to Coventry.
The former midfielder joined the management team at Coventry in 2002, after a period playing for Liverpool, and took up the post of assistant manager at Rangers last year.
The 54-year-old has 57 caps for Scotland and captained the team to the Euro 96 finals.
Fans from across the UK took to social media to send messages of support to McAllister following the attack.
Ross Lafferty wrote on Twitter: "All the best to Gary McAllister after this shocking attack. One of the most likeable men in football and a Leeds legend as well. Baffled as to why this would happen but particularly in the city he and his family made home."
Another tweet said: "Hope Gary McAllister is okay and hope CCTV identifies these vile individuals who attacked him #LeedsLegend"
John Ferris tweeted: "All the best to Gary McAllister and his wife, disgusting behaviour by thugs."
Another tweet by Timothy Watts said: "Sending best wishes to Gary McAllister for a speedy recovery."
West Yorkshire Police have asked that anyone who witnessed the attack in Leeds, or who has any information that could help the investigation, to contact Leeds CID quoting crime reference number 13190152147.