Grimsby midfielder Curtis Woodhouse is set to swap boots for gloves and embark on a career as a professional boxer at the end of the current season.
Woodhouse was the Blades' youngest-ever skipper
The former Sheffield United captain, 26, has been given the go-ahead by the British Boxing Board of Control.
Woodhouse, who has no previous ring experience, will be trained and managed by Dean Powell, who is connected to Frank Warren's Sports Network group.
Woodhouse joined the Mariners from Hull during the January transfer window.
The Driffield-born player made his debut for the Blades aged 17 in 1997 and went on to make over 100 appearances for them.
He moved to Birmingham for £1m in 2001 and made 14 appearances for promotion-chasing Grimsby in League Two.