Australia Test captain Tim Paine was "devastated" to hear of Will Pucovski's latest concussion but has nominated Marcus Harris to step in should the opener prove unfit for the Ashes.
Pucovski was struck on the helmet by a ball in a net session while training for Victoria last week.
Pucovski's history of concussion problems could mean the young opener is sidelined for at least part of the Ashes series, which starts on December 8 in Brisbane.
"I've spoken to him a bit the last few days. He is improving slowly," Paine said on radio station SEN Hobart.
"I don't think it's as bad as some of the others he's had before but with his history we have to be very careful with anything around the brain.
"I was devastated to hear it's happened again."
Australia have long hoped Pucovski might blossom into a regular opening partner for David Warner, who has seen a procession of team mates come and go since Chris Rogers played his last Test against England in 2015.
But concussions and injuries have repeatedly thwarted Pucovski.
He made his long-awaited Test debut against India in Sydney in January but suffered a shoulder injury in the match and was replaced by Harris for the fourth Test in Brisbane.
Paine said there was no problem with Pucovski's technique despite him suffering a number of blows to the head.
"He's a good player of the short ball, you don't average 54 or so in first-class cricket if you can't play the short ball," Paine said.
"I think he's now more susceptible (to concussion) than other people. He doesn't need to be hit as hard on his head."
Harris, who has been dropped twice in his 10-Test career, averaged 9.66 against England during the 2019 Ashes but Paine endorsed the 29-year-old as a likely replacement for Pucovski.
"He’s just come back from a superb six months in England playing for Leicestershire in county cricket," he added.
"And we know his first class record for Victoria has been excellent for some time now, so he's probably the frontrunner."