Chelsea have reportedly been told that Emanuel Mammana will cost them £8m.
It is believed that the versatile defender has a release clause in his contract at River Plate that is worth £11m.
However, Goal.com claims that River are prepared to accept a lesser fee to help the 20-year-old finalise a quick deal.
The report adds that Mammana's agent Hernan Reguera was recently in London to hold initial negotiations with the Stamford Bridge outfit.
Further speculation has claimed that Italian duo Fiorentina and Inter Milan are also in the running to sign the one-capped Argentina international.
