Jones, a Sydney Cricket Ground trustee and a friend of the injured 25-year-old, said Thursday was a critical day in the treatment of Hughes, who is in an induced coma after suffering an injury that was "much more serious than anyone had imagined".

A clearly emotional Jones said on his 2GB radio program on Thursday that he had been told that the "neurology is very, very bad, or in the language that the layman understands, the brain is very sick".

"What happened is that the blow from the cricket ball damaged ... a major artery in the back of his head and that caused bleeding over the skull and prevented blood from going to the brain," Jones said.

"Today is a critical day. I repeat, this is much more serious than anyone imagined. Medical technology is currently breathing for him. The brain is very sick and we pray for miracles."

So traumatised was Jones that, as he attempted to praise the left-handed batsman on air, he could not finish his tribute and was forced to cut prematurely to an advertisement.

"He's a very special young man, this fellow, and, well, I guess I'm just grateful that ... hmm ... ," Jones said, before the advertisement cut in.

Jones was seen visiting St Vincent's Hospital about lunch-time on Thursday, the latest in a string of high-profile visitors who have rushed to be by the cricketer's bedside.

Australian captain Michael Clarke has been a constant presence at the hospital, along with Hughes' mother, father and sister.

Cricketers Aaron Finch, Matthew Wade and Peter Forrest flew to Sydney from interstate to visit Hughes, while Finch and wicket-keeper Brad Haddin were seen embracing outside the hospital.

Ricky Ponting, Peter Siddle and Simon Katich were also seen at St Vincent's on Thursday afternoon.

Jones said he knew Hughes "very well".

"He has not only been in my home on many occasions but we text regularly," Jones said.

"He was often in and out of the Test team, and that used to upset him a bit, and I'd try to keep his morale up, kept him believing that, well, he could be as good as he wanted to be.

"He'd always reply with excitement, gratitude, and then we'd always end up with a bit of racing talk. I guess I'm not the only one who hasn't been able to sleep much or even move without thinking about the young man."

Hughes' fellow cricketers were "utterly traumatised" by the injury suffered during the Sheffield Shield clash between South Australia and NSW at the Sydney Cricket Ground on Tuesday afternoon, Jones said.

Jones also believed the Test match between Australia and India, slated to start next Thursday in Brisbane, should be cancelled.

"In my view there should be no Test match next week against India. This is very, very difficult for cricket to bear," Jones said.

But he also said Hughes would not want anyone to feel responsible for his injury.

"Phillip would never be blaming anyone. He wouldn't want a debate about whether there should be bouncers or not. There should be no blame, he loves his cricket," Jones said.