Lock Maro Itoje has been ruled out of England’s third and decisive test against Australia on Saturday because of concussion.
Itoje, 27, suffered a head knock in the Brisbane test and had already been ruled out of the series decider at Sydney Cricket Ground.
Flanker Sam Underhill has also been ruled out, leaving coach Eddie Jones with a potential shortage of backrowers. England said they would not be replaced.
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.
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 number seven shirt on Saturday.
Australia also have a lengthy injury list and called winger Mark Nawaqanitawase and lock Lukhan Salakaia-Loto into their squad on Monday.