Anthony Crolla is suffering from head injuries after he was allegedly struck by burglars during a confrontation at his home on Tuesday night.
The lightweight boxer from Manchester, 28, is thought to have been hit across the head with a concrete slab by one intruder.
He was subsequently taken to the Royal Oldham Hospital, where he is stable and set to undergo a brain scan.
He also suffered a broken ankle.
Crolla had reportedly attempted to disturb the two after he heard the intruders break into the house next door to his.
Crolla's trainer Joe Gallagher said before going in to see the fighter in hospital late last night: "He's got head injuries and we don't know the severity of them yet. He's having a CT scan.
"I tried talking to him before but he's concussed.
"The next door neighbours were being burgled, and the burglars came into his garden. He gave chase, and apprehended one of them, and the other one lifted a slab of concrete and hit him with it, and he fell and broke his ankle."
Sports promoter Eddie Hearn tweeted: "Gutted to confirm that ant-crolla is in hospital with a head and ankle injury after confronting burglars at/near his property."
Crolla, 28, from Manchester - known as "Million Dollar" - has fought in the super featherweight and lightweight divisions and is the current holder of the WBO inter-continental lightweight title after beating Gavin Rees.
He was due to face Richar Abril from Cuba for the WBA world lightweight title in Manchester on January 23 - but Mr Hearn tweeted that the fight was off.
"Anthony is in a stable condition in Oldham hospital. Unfortunately the Jan 23rd fight is off but concerns right now are with Ant and family," he posted.
"You ask anyone in boxing doubt you could find a nicer kid than Crolla, absolutely gutted for him."
"To have the world title shot in Manchester is a huge factor," Crolla said previously ahead of the bout.
"Without wanting to sound cheesy, it doesn't get any bigger than that. I am a Manchester lad so to be fighting in Manchester for a world title, I couldn't ask for anything more and the only way it could get better than that is to go out there and win it."
Additional reporting by PAReuse content