Michael Essien has cut short his loan spell at Real Madrid to return to Chelsea temporarily for treatment on a troublesome injury.
The 29-year-old joined ex-Chelsea boss Jose Mourinho at the Bernabeu at the beginning of the season, but the Ghanaian has been on the sidelines since November 11.
And Essien has responded badly to treatment in Madrid, so has returned to west London in an effort to improve his rehabilitation.
Real Madrid's assistant manager, Aitor Karanka, revealed that Essien's inability to respond to rehab in Spain is the principal reason for his return to Stamford Bridge.
"Essien is not injured but is suffering from an allergic reaction to a drug," Karanka was quoted as saying on Goal.com.
The Ghana international has struggled with injury troubles over the last few seasons, and only managed to make 14 appearances for the Blues last season. His limited availablity convinced Chelsea to let him leave on loan, with Ramires, John Obi Mikel and Frank Lampard ahead of him in the Blues pecking order.
But Real Madrid are confident that his latest complaint can be addressed quickly, and that Essien will return to the Bernabeu to continue his loan spell in the New Year.
The reigning La Liga champions have struggled this season, and currently sit third in the league, 11 points behind table topping Barcelona.
Essien was primarily used as a substitute during his time at the Bernabeu, and even made several appearances at left-back.