Tomas Kalas signs Chelsea contract extension

Chelsea have announced that defender Tomas Kalas has signed a new three-year contract with the club.

The 22-year-old Czech recently returned to Middlesbrough on a season-long loan.

He has made four senior appearances for Chelsea since arriving at Stamford Bridge from Sigma Olomouc in 2010.

Kalas has been loaned out to Vitesse Arnhem and FC Koln in recent seasons, while he spent the second half of the last campaign with Boro.