Rob Webber has been added to England's preliminary squad for next month's tour to New Zealand and the fixture against the Barbarians on June 1.
The Bath hooker's hopes of facing the All Blacks hinge on recovering from a knee problem and he faces a race against time to be ready for the first Test on June 7.
England's resources in the number two jersey have been stretched by Dylan Hartley's shoulder injury and Tom Youngs' unavailability due to family reasons.
Webber is third choice in the position but, if he regains fitness, could find himself involved against the All Blacks with Hartley's participation uncertain.
"We've brought Rob in for further assessment and treatment in order to give him the best possible chance of making the tour to New Zealand," head coach Stuart Lancaster said.
England have added 18 players to their squad from beaten Aviva Premiership semi-finalists Harlequins and Leicester, along with Sale's James Gaskell and Ross Harrison.
England squad additions: A Allen (Leicester Tigers), M Brown (Harlequins), R Buchanan (Harlequins), D Care (Harlequins), W Collier (Harlequins), J Gaskell (Sale), J Gibson (Leicester Tigers), J Gray (Harlequins), R Harrison (Sale), G Kitchener (Leicester Tigers), J Marler (Harlequins), C Matthews (Harlequins), G Parling (Leicester Tigers), C Robshaw (Harlequins), E Slater (Leicester Tigers), K Sinckler (Harlequins), M Tuilagi (Leicester Tigers), L Wallace (Harlequins), D Ward (Harlequins), R Webber (Bath), B Youngs (Leicester Tigers).