Chelsea have confirmed they have reached an agreement with Anzhi Makhachkala to sign Willian, subject to a work permit hearing on Wednesday.
The Blues have beaten London rivals Tottenham Hotspur in the race to sign the Brazilian midfielder, who underwent a medical with the north London club last Wednesday ahead of a prospective move to White Hart Lane.
But as hinted by Jose Mourinho in a press conference on Friday, Chelsea have hijacked a deal for the 25-year-old and have now sealed a deal having agreed a fee -reportedly worth £30m - and agreed personal terms with the player.
Tottenham had hoped to secure a deal for Willian this week as the club begin to make plans for life without Gareth Bale, who flew out to Spain the finalise his world record move to Real Madrid on Saturday.
BBC Sport suggest the transfer was made possible when Chelsea owner Roman Abramovich intervened and directly contacted fellow Russian oligarch and Anzhi owner Suleyman Kerimov.
Once the clubs had agreed on a fee, the prospect of playing Champions League football proved to be instrumental in Willian's decision to make a move to west London.
Following reports suggesting Chelsea had made late efforts to sign the former Shakhtar Donetsk star on Thursday, Mourinho strongly hinted his side had won the race for his signature.
When asked of Willian, Mourinho told the press, "I think he has already made his decision," before nodding in the affirmative when asked if that was Chelsea.
"I don't like to speak before time because football can be crazy. I know what the player wants, so in this moment we cannot hide. That is possibility."
Despite the imminent arrival of the Brazilian, Chelsea are still hoping to strike a deal with Manchester United to bring Wayne Rooney to Stamford Bridge.
The Premier League champions have already rejected two bids, but will receive a third from the Blues following the meeting between the two clubs at Old Trafford on Monday night.
Despite United's desire to hold onto the England striker, Mourinho insists David Moyes should have no qualms about selling the 27-year-old to a Premier League rival, claiming such a move is better for the league rather than one to a club elsewhere in Europe.
"The old-fashioned mentality of 'I don't sell players to the same country' doesn't help the market and doesn't help the players," Mourinho was quoted as saying by Sky Sports.
"Sometimes you push players abroad when you should be interested in keeping them in your league, because when you keep players in your league you are contributing to make your league the best league.
"So when you want to sell and you are pushing the players abroad I think you are giving the wrong contribution to the league where you are."