Spain midfielder Cesc Fabregas has joined Chelsea from Barcelona after agreeing a five-year deal.
Fabregas, 27, will return to London after leaving Arsenal to join his boyhood club in 2011.
"I do feel that I have unfinished business in the Premier League and now is the right time for my return," Fabregas told Barcelona's website (fcbarcelona.com).
"Everyone knows that Arsenal had the first option to sign me. They decided not to take this option and therefore it wasn't meant to be. I considered all the other offers very carefully and I firmly believe that Chelsea is the best choice. They match my footballing ambitions with their hunger and desire to win trophies."
Fabregas, who played for Barcelona as a child before joining Arsenal aged 16, made 151 appearances under three coaches, scoring 42 times for the Catalans but never proved a favourite among fans.
He joins Jose Mourinho's Chelsea side that finished third in the Premier League and reached the semi-finals of the Champions League last season, but that had trouble scoring goals.
Fabregas, who is in Brazil with Spain for the World Cup, is likely to team up with prolific Atletico Madrid striker Diego Costa, a much publicised transfer target for Mourinho, at Stamford Bridge next season.