Michael Essien has returned to Chelsea to discover exactly what his unknown injury sustained on loan with Real Madrid actually is.

The Ghanaian midfielder was sent on a season-long loan to the Spanish champions but has not played in Jose Mourinho's side since mid-November as he seeks treatment on a problem that has not yet been diagnosed.

Real assistant Aitor Karanka revealed that Essien had suffered an allergic reaction to medication he was taking but it has also been suggested that he has missed action due to feet and leg problems.

Essien returned to London on Friday and trained at Chelsea's Cobham training ground as he continues to recover.

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