The 25-year-old Belgium international has attracted widespread interest ahead of the transfer window after a scintillating start to the 2012/13 campaign.
Fellaini has netted eight Premier League goals already, and Chelsea have been heavily linked with an attempt to lure him to Stamford Bridge in the New Year, adding to a growing contingent of Belgians in west London, with Eden Hazard the latest, and highest profile name through the door.
Citizens boss Roberto Mancini is also a long-term admirer of the Toffees star, and could try and add him to his Etihad Stadium squad, as City step up the defence of their Premier League title.
However, both Chelsea and Manchester City will face stiff competition for Fellaini's signature, after a Zenit source confirmed that the Russian club's coach Luciano Spalletti is eager to reunite the 6ft 4in attacker with international team-mate Axel Witsel at the Petrovsky Stadium.
"The management expect to strengthen midfield. The signings will be of high quality," the source told The Sun. "Belgium international Marouane Fellaini is on the list. He has clearly proved himself for Everton."