Brazil midfielder Willian completed his move to Chelsea as speculation intensified he could be joined at Stamford Bridge by his former team-mate Samuel Eto'o.
The twice-capped 25-year-old was finally granted a work permit on Wednesday to complete his move from Russian club Anzhi Makhachkala after agreeing a five-year contract with the Blues.
And with their attempts to sign Wayne Rooney from Manchester United seemingly floundering, Chelsea were reported to be on the verge of signing another Anzhi player in the form of Cameroon striker Eto'o.
On Thursday morning pictures emerged of the 32-year-old, who has been widely linked with a move to Stamford Bridge over the last few days, apparently arriving at London St Pancras station on Wednesday night.
Chelsea are keen to increase their attacking options, while Anzhi have been offloading players after owner Suleyman Kerimov decided to reduce his spending at the Dagestan club.
And Willian, who was poised to join Tottenham before Chelsea made their move, admitted the lure of working with the Portuguese was a big factor in his decision to join the west London club.
"I'm very happy to be here, it's been a dream of mine to come and play here," Willian said on Chelsea's official website.
"Chelsea are one of the best clubs in the world and now I'm going to play for one of the best managers in the world. I'm very happy and looking forward to it."
Willian, who will wear the number 22 shirt, looked set to join Spurs last week only for Chelsea to hijack the deal and outbid their Barclays Premier League rivals.
He had passed a medical at Spurs before Mourinho swooped to add him to Chelsea's attacking options.
He began his career in his homeland with Corinthians before moving to Europe with Shakhtar Donetsk in 2007. He made over 100 appearances for the Ukrainian club before moving to Anzhi.
His arrival has fuelled speculation that unsettled Spaniard Juan Mata could be on his way out of Stamford Bridge with Arsenal a possible destination.