Chelsea have confirmed that they have agreed terms with both Willian and Anzhi Makhachkala for the transfer of the attacking midfielder.
The Brazil international seemed set to sign for Tottenham after undertaking a medical at the club on Thursday, but Chelsea came in with a late bid.
And Jose Mourinho is looking to complete a double swoop after it was revealed Chelsea are in talks with the Russian club over striker Samuel Eto'o.
Shock: Willian nearly signed for Tottenham before joining Jose Mourinho's Chelsea
Delight: Willian revealed his delight at his move to Chelsea on Instagram
Movement: Chelsea are holding talks with Anzhi over Samuel Eto'o
The transfer of Willian is subject to a work permit hearing on Wednesday.
Hours after terms were agreed, William revealed his delight at the pending move on his Instagram account: 'My dream come true!! Im very happy to sign with a best club in the world. Thanks God!! COME ON CHELSEA!!!.'
The 25-year-old flew in to England last week, expecting to sign terms with Tottenham to replace Gareth Bale after initial conversations with Liverpool.
He even had a medical at Spurs' training ground, but was said to be 'considering his options', thought to be looking for Champions League football.
Chelsea were that option, eventually completing a transfer thought to be in the region of £30million, also offering him a slightly better financial package.
Snub: Willian was all smiles pictured outside a city hotel before his Tottenham medical but has opted to move to Chelsea
New-look Chelsea this season?
Jose Mourinho revealed at a press conference on Friday that be believed Willian had made his decision and was picking west London over the north, with the winger meeting his new team-mates on Saturday.
Daniel Levy was intent on signing the star as a replacement for Real Madrid-bound Bale, along with Roma's Erik Lamela, and is sure to be outraged by Chelsea's snatch.
The 'Special One' was full of laughter when he met the media on Friday, mocking Spurs saying: ‘The best thing you can do is do the medical in secret. If the player is fine, you can sign him. If the player is not fine, you don’t destroy his career by saying the player has problems, so you do it in secret and after that sign the contract.’
With the amount of attacking midfielders at Mourinho's disposal, it is unclear where Willian will fit in at the club.
Oscar, Eden Hazard, Victor Moses, Kevin De Bruyne, Andre Schurrle, Marco Van Ginkel and Juan Mata all fighting for a No 10 role, though there is some doubt over the Spaniard's future.
Willian has been linked with a move to the Premier League for many years, impressing in the Champions League with Shakhtar Donetsk.
Familiar: Willian played for Shakhtar Donetsk against Chelsea in the Champions League last season
He almost completed a transfer to Chelsea back in 2011 when Andre Villas Boas was in charge, and the pair have kept in touch since, hence Spurs' involvement in the transfer.
After scoring ten goals in 55 European appearnces, and lighting up the domestic stage too, he surprisingly made the move to mega-rich Russian side Anzhi.
The 25-year-old only spent eight months at the club though, playing ten games, before the side had to sell some of their major assets because of financial issues.