Lotus boss Tony Fernandes steps up his bid for West Ham
Fernandes has been a regular at West Ham's home games for many years
Lotus F1 team boss Tony Fernandes has joined Italian Massimo Cellino as a front-runner in the race to buy West Ham, BBC Sport understands.
Ex-Birmingham City owners David Gold and David Sullivan and finance company Intermarket were in the hunt but are now believed to be outsiders.
Cellino is the president of Serie A side Cagliari, where Hammers boss Gianfranco Zola ended his playing days.
He is already in London, with Fernandes set to fly in before the weekend.
Italian journalist Massimo Marianella told BBC Radio 5 live: "The deal (with Cellino) is not 100%, the Premier League is now checking his past and the real economic situation. Tony Fernandes is still a real option."
It is understood West Ham will not engage in any activity in the January transfer window until the takeover situation is resolved.
Sources close to the east London club have indicated a deal could be completed by the end of the week.
All four interested parties claim to have connections with the Upton Park outfit, and it could be the £100m asking price is reached.
Gold and Sullivan say they are long-standing Hammers fans and would make money available for Zola to spend on transfers.
Intermarket, which was hit by the death at the weekend of chief executive officer Jim Bowe, is believed to have former West Ham striker Tony Cottee as an adviser but must prove it has the funds to secure a deal.
Air Asia founder Fernandes has been a regular at home matches for many years.
Cellino, who was sighted at QPR's home match on Tuesday, has publicly stated his admiration for former Italian international Zola, saying: "He left football with the same class he had on the pitch."
But sources in Italy suggest the pair actually have a thorny relationship and that former Cagliari boss Daniele Arrigoni, a close friend of Cellino, could be brought in as manager if he wins control of the Hammers.
The club are currently owned by CB Holding, which has indicated West Ham are £38m in debt.
The main shareholder in CB Holding is Icelandic bank Straumur, which has previously said it is in no hurry to sell the club although that was before the various bidders became known.
Zola has insisted he will not have to sell his star players in the January transfer window.
England goalkeeper Robert Green, defender Matthew Upson and Carlton Cole have all been linked with interest from big clubs.
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