Australia batter Steve Smith was ruled out on the morning of the crucial third Ashes Test against England following symptoms of nausea and dizziness.
Smith was replaced in the Australia line-up by Usman Khawaja.
The 36-year-old missed training on Monday because of illness, then was struck in the groin when he batted in the nets on Tuesday morning.
A statement from Cricket Australia said: “Over the past few days he [Steve Smith] has been feeling unwell, with symptoms including nausea and dizziness.
“He was assessed and monitored closely and was close to being available to play. However, given the persistence of symptoms, a decision was made not to proceed.
“He is being treated for a potential vestibular issue. This is something Steve has experienced intermittently in the past and is being managed accordingly. He is expected to be available for the Boxing Day Test in Melbourne.”
Smith was on the outfield at the Adelaide Oval before play began, only to leave the stadium before the toss took place.
“Steve has been feeling a little bit unwell over the past couple of days,” said Australia captain Pat Cummins.
“He gave it a crack this morning, but didn’t think he was going to get up for this one. He’s headed off home.
“We’re pretty lucky we’ve got someone like Usman who can step right in.”
Khawaja, who was left out of the Australia XI when it was named on Tuesday, comes in to take Smith’s place at number four.
Australia, 2-0 up after wins in the first two Tests, will retain the Ashes if they avoid defeat in Adelaide. The hosts won the toss and chose to bat first.