Australia and Sydney Sixers bowler Joe Mennie is in hospital after scans revealed a fracture to his skull and bleeding on the brain.
It is the second time Mennie has been treated for the issue.
Mennie copped a ball to the head on Monday and underwent tests in hospital but was released that evening.
Mennie has since been sent back to hospital for observation.
"Whilst this is a serious injury, Joe is feeling well. We believe that this is a stable injury and will not require surgery," Cricket Australia chief medical officer Dr John Orchard said.
"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 debuted for Australia against South Africa last year.
The Sixers face the Brisbane Heat tonight in their Big Bash League semi-final.