Chelsea defender Tomas Kalas has completed a transfer to Middlesbrough on loan until the end of the season.

Jose Mourinho has allowed the highly-rated Czech international to join the Championship outfit to play under Aitor Karanka, who previously worked as the Chelsea manager's assistant boss at Real Madrid.

Middlesbrough have confirmed on their official website that Kalas will join up with the team following a short loan stint at German side FC Koln.

Kalas, who signed for the Blues in 2010, has featured twice for the Chelsea first team.