Flanker Sam Underhill has been ruled out of England's third and deciding Test against Australia because of concussion, leaving coach Eddie Jones with a potential shortage of backrowers.
Underhill started at openside flanker in the 25-17 victory in Brisbane last Saturday in place of Tom Curry, who returned home after suffering a concussion in the 30-28 first Test loss in Perth.
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Lock Maro Itoje also suffered a head knock in the Brisbane Test and had already been ruled out of the series decider at Sydney Cricket Ground.
"Maro Itoje and Sam Underhill have been withdrawn from the England squad after suffering concussions in last weekend’s win against Australia," the RFU said in a statement. "No replacements will be called up."
Wasps flanker Jack Willis is also a doubt after being forced to withdraw from the England replacements in Brisbane because of a rib injury.
Lewis Ludlam came off the bench in the first two tests and looks the most likely starter in the No.7 shirt on Saturday.
It comes as Underhill missed three months earlier this season after sustaining two head knocks in December.
“When it comes to concussions, player welfare is always now first and foremost,” said Underhill last Tuesday
“There is no grey area – you are either okay or you are not and if you are not okay you are looked after. It’s always a frustrating injury because you can’t do an awful lot.
“One of the symptoms is tiredness so you don’t want to be falling asleep, it’s more of a symptom check.
“You have obviously got a return to play protocol so you check off bike, run, some training, and it can get fairly menial and tedious doing the same thing over and over again.
“It’s physically fairly basic and you can’t do an awful lot. That’s why it’s frustrating.”
