Joe Mennie has returned to hospital after scans revealed he suffered minor bleeding on the brain and a fractured skull after being struck in the head at training with BBL side the Sydney Sixers.
Fast bowler Mennie was initially thought to have escaped serious injury after being felled on Monday night at the Gabba.
He was taken to hospital in Brisbane for observation and discharged.But the 28-year-old has returned to hospital as a precaution, Cricket Australia chief medical officer John Orchard said.
"Joe was reviewed by a Cricket Australia doctor on Tuesday and had some scans performed that revealed a small fracture and associated minor brain bleed," Orchard said in a statement on Wednesday.
"Whilst this is a serious injury, Joe is feeling well.
"We believe that this is a stable injury and will not require surgery.
"As a precautionary measure, Joe has been admitted to hospital for observation and will continue to be assessed by a neurosurgeon to determine best course of action."
Mennie was preparing for Wednesday's semi-final against Brisbane Heat when he was struck.
Sixers veteran Brad Haddin described the incident as "scary".
"He was bowling in the nets and (batsman) Michael Lumb got hold of one straight back and he's followed through and got him in the head," Haddin told Sky Sports Radio on Tuesday.
Mennie, who made his Test debut for Australia against South Africa in November, joined the Sixers in April following three summers with Hobart.
He has played just twice for the franchise this season, most recently against the Hurricanes in Sydney on December 23.