Chelsea have announced they have reached an agreement with Anzhi Makhachkala for Willian, subject to a work permit hearing on Wednesday.
ESPN learnt on Friday that Willian had opted to join Chelsea rather than Tottenham, with the Blues agreeing a £30 million deal with Anzhi to sign the forward.
Chelsea moved for the Brazil international after it looked as though he was set to move to Spurs, having undergone a medical with the North London club.
Blues boss Jose Mourinho intimated a deal was close in his press conference ahead of Monday's meeting with Manchester United, while also insisting that Juan Mata is not for sale.
A statement on Chelsea's official website read on Sunday morning: "Chelsea Football Club can confirm an agreement has been reached with both Willian and his club Anzhi Makhachkala for the transfer of the Brazilian player.
"The transfer is subject to a work permit hearing on Wednesday."