Alex signs new Chelsea contract
Alex, who has been sidelined by a groin injury, is yet to play under new coach Carlo Ancelotti but the Italian said he was delighted he had agreed a new deal.
"I am very happy Alex has signed a new contract," Ancelotti told the club's website. "He is just returning from surgery but he is a player I know well. I am familiar with his fantastic qualities."
Chelsea, banned by governing body FIFA from signing new players until 2011 after being found guilty of inducing Racing Lens teenager Gael Kakuta to break his contract, also secured striker Salomon Kalou on a new three-year deal on Monday.