Chelsea signed Spanish midfielder Oriol Romeu from Barcelona on a four-year contract on Thursday.

The 19-year-old defensive midfielder, who played for Spain at the under-20 World Cup in Colombia, completed the 5 million euro ( 7 million dollars).

Romeu, who made two appearances for Barcelona's first team last season, will help fill the void left by Michael Essien, who has been ruled out for six months after injuring his right knee.

"It is a part of the squad in which we are struggling with numbers because of Michael Essien's injury and Oriol is a player with a bright future," Chelsea manager Andre Villas-Boas said.

Barcelona said in a statement the Oriol deal was worth 5 million euros with a buy-back option. The Spanish champions would pay 10 million euros at the end of next season for him, 15 million euros the year after.

Romeu is Chelsea's second offseason signing after Belgian goalkeeper Thibaut Courtois, who was immediately loaned to Atletico Madrid after his move from Genk.