Sydney - Australian batsman Phillip Hughes was to have more scans Wednesday after surgery to relieve pressure on his brain as players rallied around the bowler who inflicted the damage.
VIDEO:Phil Hughes critical after being struck by bouncer
The 25-year-old, who was pressing for a Test recall, was knocked out by a Sean Abbott bouncer in a freak incident at the Sydney Cricket Ground on Tuesday, crumbling to the ground unconscious after the heavy blow to the lower head.
He underwent surgery and was in an induced coma in intensive care at St Vincent's Hospital.
"Phillip Hughes remains in a critical condition in St Vincent's Hospital after being struck in the head while batting for South Australia against NSW at the SCG yesterday," Cricket Australia said in a statement.
"He will have scans this morning and a further update will be provided when the results of those scans are known."
Test captain Michael Clarke was one of the first to arrive at the hospital on Wednesday, resuming a vigil at his close friend's bedside and comforting Hughes's mother and sister.
Hughes made his Test debut in South Africa in 2009, where he made 75 in the second innings at Johannesburg. The left-hander followed up in the second Test at Durban with centuries in both innings, amassing some 275 runs at the crease.
The runs dried up and despite playing 26 Tests he has never secured a regular place in the team, partly due to his perceived weakness against the short ball.
But with doubts over the fitness of Clarke for the first Test against India next month in Brisbane, he was seen as a potential replacement. Shaun Marsh is now the frontrunner.
The popular Hughes was wearing a helmet when he was struck but manufacturer Masuri said he was not wearing their most up-to-date model.
"From the footage and pictures currently available to Masuri, it appears that Phil Hughes was struck by the ball to the rear of the grille and below the back of the shell, missing his Masuri Original Test model helmet," the company said.
"This is a vulnerable area of the head and neck that helmets cannot fully protect, while enabling batsmen to have full and proper movement."
Hughes was attempting a pull shot when he was hit, and fell badly.
Medical staff worked on him, including mouth-to-mouth resuscitation and oxygen, for more than 30 minutes before he was taken from the field and rushed to hospital on life-support.
While it remains unclear how badly he may be hurt, advocacy group Brain Injury Australia said generally that recovery was a long process, although no two injuries were the same.
"Recovery from brain injury is a marathon, not a sprint," said spokesperson Nick Rushworth, who had his own brush with death in 1996 in a cycling accident.
Up-and-coming bowler Abbott, who made his one-day and Twenty20 debut for Australia in October and is just 22, was seen cradling the injured player immediately after the incident.
"It says a lot about Sean doesn't it," Cricket Australia chief James Sutherland said, calling it a "freak, freak accident".
"Sean will have all the support he needs around him."
Cricketers from around the world have rallied behind not just Hughes but also Abbott.
"Stay strong @seanabbott77. Not your fault young man," tweeted former Australian great Dean Jones, while Damien Fleming said: "Feeling for Sean Abbott who was just bowling a cricket ball."
Cricket Australia said all current domestic Sheffield Shield matches had been abandoned in the wake of Hughes's injury, with official Pat Howard saying "it's just not the day to be playing cricket".