The 22-year-old felt what Frank Lampard described as 'a small sensation' in his hamstring during the warm-up at Burnley at the end of last month and hasn't featured for the Blues since.

He was named in the USA squad for upcoming friendly internationals against Wales and Panama, joining the camp ahead of their game in Swansea this week, but Berhalter has confirmed that he won't feature and will instead return to Cobham for further treatment.

'Christian is a big part of our group,' Berhalter said. 'He has been working through an injury but it really says a lot that he wanted to come into camp, be around the guys and continue to be a leader with this team.'