Chelsea signed Valencia winger Juan Mata to a five-year contract, the Premier League club said on its website.
Mata scored 43 goals in 179 games over the past four seasons with Valencia. The 23-year-old becomes the fourth signing for new Blues manager Andre Villas-Boas, after Oriol Romeu, Romelua Lukaku and Thibaut Courtois.
Mata has made 11 appearances for the Spanish national team. He also captained Spain to the title at the Under-21 European Championship this summer.