The Belgian midfielder recently signed a new 5-year-deal at Goodison Park in 2011, however it is understood that deal included a clause that allows him to leave Everton if a bid of £22 million or more comes in from a Champions League club.
Chelsea recently capitalised on a similar clause by signing former Newcastle United forward Demba Ba earlier this month, and it is believed the Blues want to add further to their ranks and will use similar tactics to lure the impressive Toffees midfielder to the Bridge.
Midfielder Frank Lampard has finally admitted that his career is over with Chelsea, after his agent confirmed "in no circumstances" would he be offered a new contract to stay beyond this season.
His current deal is set to expire this summer, and Manchester United manager Sir Alex Ferguson has reportedly shown an interest in signing the England international and has asked to be kept informed about future developments.
An offer to join United might be too tempting for Lampard to resist, particularly as he feels he still has a lot to give at the top levels having captained the Blues to Champions League glory only last May.