Mourinho had said at the end of the season that he wanted to bring three fresh faces to the club, and Mikel has joined Andriy Shevchenko, Michael Ballack and Salomon Kalou as the Premiership champions look to defend their title.
In addition, Portuguese goalkeeper Hilario is expected to arrive as cover for Petr Cech, while Mourinho has confirmed his interest in Real Madrid's Brazil left-back Roberto Carlos. With William Gallas, Carlton Cole and Shaun Wright-Phillips appearing unsettled, more changes are expected soon. Eidur Gudjohnsen, Hernan Crespo and Jiri Jarosik have also been linked with moves.
Chelsea officials will be hoping that any negotiations will not be as prolonged as the Mikel saga. Manchester United, who thought they had secured the midfielder in 2005, accepted a £12m settlement to pave the way for the 19-year-old Nigerian to become a Chelsea player after the rival clubs reached an agreement over his future.
The two Premiership sides, along with Mikel's Norwegian club Lyn Oslo, who received £4m, worked together to allow Mikel to join the champions after a bitter transfer dispute. Chelsea will pay half of both amounts now and half in 12 months' time.
After agreeing to join United, Mikel subsequently claimed he had been pressured into signing the contract and wanted to join Chelsea instead. "As a result of this settlement all claims in this matter, which Chelsea were never an official party to, are now withdrawn," read a statement issued by Chelsea and United. "The payments do not in any way imply the acceptance of any such claims and have been made solely so that Mikel can resume his career.
"United will support Chelsea in any work permit application if necessary. All parties have agreed there will be no further comment on the settlement or any of the allegations or claims."
The overall price tag will heap pressure on the youngster, who has been billed as one of the hottest teenage prospects along with players such as Theo Walcott, Lionel Messi and Cesc Fabregas. Mikel's first challenge will be to break into the Chelsea first team, which Wright-Phillips failed to do following his £21m move from Manchester City. With Claude Makelele, Frank Lampard, Ballack, Joe Cole and Arjen Robben established in midfield, Mikel is likely to be used sparingly at first.
Wolves centre-back Joleon Lescott has passed a medical and agreed personal terms with Everton. The 23-year-old is moving to Goodison Park in a deal worth about £5.5m.Reuse content