Courtney Lawes has left England's autumn international training camp in Portugal because of a back injury, the Rugby Football Union confirmed on Saturday.
Lawes has returned home from the camp in Vilamoura to undergo treatment on a pre-existing back injury but is expected to return to the squad next week.
He now faces a race to be fit ahead of England's autumn international opener against South Africa at Twickenham on Nov. 3.
"Courtney Lawes will return to England today for specialist treatment on a pre-existing back injury," England's forwards coach Steve Borthwick said.
"He is expected to return to Portugal early next week. He has taken part in modified training this week."
Eddie Jones' squad has already been depleted by the injuries to key players such as Chris Robshaw, Joe Launchbury and Billy and Mako Vunipola.
As well as South Africa, England will also play New Zealand, Japan and Australia across consecutive weekends next month.