England's replacement scrum-half Dan Robson is undergoing medical checks after being ruled out of Saturday's Guinness Six Nations clash with Scotland through illness.
Robson was poised to win his third cap as Ben Youngs' understudy for the climax to the tournament at Twickenham but will now be replaced on the bench by Saracens' Ben Spencer.
"Dan is not available and has left camp. He's got some investigations and consultations going on. We're trying to investigate exactly what's wrong," forwards coach Steve Borthwick said.
Spencer won both of his caps as a replacement on last year's tour to South Africa and Borthwick views his former Saracens team-mate as a ready-made replacement for Robson.
"I was fortunate enough to play with Ben. He's a good player. He's fast, fit and has real good fundamentals of the game. He can pass well and kicks well," Borthwick added.
"He's had time with us last year and knows our principles of play. He's played with and against a lot of the players here, so knows them well."
