England centre Benhard Janse van Rensburg has been stood down from rugby after suffering two serious concussions in his last three games.
The Bristol Bears star will miss all four of England's November Tests.
A specialist has told the 29-year-old to avoid contact rugby for several weeks.
Janse van Rensburg was knocked out while trying to tackle Henry Pollock against Northampton Saints on October 3.
It was his second major head injury in three games.
He had also left the field on a stretcher during England's win over Argentina in July.
Steve Borthwick confirms England blow
England boss Steve Borthwick has now shared an update on the inside centre.
Speaking ahead of the November Tests, he said:
"Benhard has seen a specialist and been advised to take a number of weeks of non-contact work before his reintroduction to rugby over the coming weeks."
His comments were reported by RugbyPass.
The news means Janse van Rensburg will miss games against Australia, Japan and New Zealand.
He will also sit out the Nations Championship finals weekend.
It is a cruel blow for the centre, who made his England debut against Fiji in July.
He had hoped to build on that first two caps from the summer this autumn.
Instead, he must wait for the all-clear before he can play again.
There is no set date for his return.
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More England stars ruled out
Janse van Rensburg is not the only player giving Borthwick a headache.
Bath flanker Guy Pepper will also miss the November Tests due to an ankle injury.
Northampton fly-half Fin Smith is a doubt too.
He has a calf injury but Borthwick hopes he will be fit to face Australia on November 8.
A call on his fitness is due next Wednesday.
There is some good news for England fans.
Seb Atkinson and Immanuel Feyi-Waboso could both play for their clubs this weekend.
Borthwick will hope they come through those games with no fresh injury fears.
Pick your England XV
Who should start against Australia? With key players out, Steve Borthwick has some big calls to make.
Now it's your turn. Pick your England XV and see how your team compares with other fans.
