Chelsea could end up forking out a mind boggling £100million for Atletico Madrid sensation Sergio Aguero should the Argentine swap the Vicente Calderon for Stamford Bridge in the New Year.

The astronomical figure includes the initial transfer fee, additional add-ons, agents fees and "Kun's" wages.

ESPN claim the initial fee for the 21-year-old is £40million, with another £10million to be paid in add-ons if Chelsea win major honours or if Aguero scores a certain amount of goals for the Blues.

A deal of that magnitude would be smash the previous British transfer record when Manchester City shelled out
£32.5million to lure Robinho from Real Madrid in the summer of 2008.

Aguero's wages are supposedly to be on a scaled up basis, and will eventually reach £250,000-a-week in the last years of his contract, with reports suggesting Chelsea are keen to tie him down to a six-year deal.

With the addition of various agent's fees in the millions and several other bonuses written into Aguero's contract, that brings the total cost of the Argentine playing at Stamford Bridge to just short of nine figures!

The report also suggests that Chelsea tried to sign the player this past summer, but were put off by the then asking price of £60million and Aguero's wage demands of £6million-a-year.

Blues boss Carlo Ancelotti wants to bring in at least one marquee name this winter, as he is aware it will most likely be his last active transfer window until the summer of 2011, and is also keeping an eye on Bayern Munich's Franck Ribery.

A source of ESPN Soccernet stated that the deal to take Aguero to Chelsea is probably now at 50-50.

"There is still more talking to do, but let's see. There is now a possibility, although with so many complications involved you would have to say it's still 50-50 whether it will finally go though."

It is believed Atletico's reluctantance to part with their prized asset and Chelsea owner Roman Abramovich still not being entirely convinced that spending that much for one player is a smart business move are the main stumbling blocks.

The source added: "Money was the problem the deal fell through in the summer, and the money is the problem now, but we shall see, as I said, the talks are on going and everyone seems to want to find a solution."