Chelsea are pushing Atletico Madrid to complete their part of the deal that will see Diego Costa move to Stamford Bridge for £32 million, reports The Daily Mail.
The Brazilian-born striker has been widely expected to join Chelsea for several months and a number of reports insist a deal has moved within touching distance.
Jose Mourinho has already met Costa's buyout clause, forcing Atletico to accept the offer and allowing Costa to talk to Chelsea officials. However, Chelsea believe Atletico are dragging their heels over the deal as they hope to receive a bigger offer.
The hope from the La Liga champions is that another club will offer more money and Chelsea fear that a bidding war could end up costing them much more than they are willing to pay.
There is also the fear that a rival club could offer Costa better terms, forcing Chelsea to re-negotiate the terms believed to be agreed between the two parties several months ago. Of course, there is always the chance to Costa will be tempted by a rival offer, forcing Chelsea to move on to alternative targets.
Chelsea want the deal sealed before the World Cup, knowing that a stellar performance from Costa, who will represent his adopted country Spain, will inspire more clubs to become interested.
If Costa does sign for Chelsea, he will sign a long-term contract worth £150,000-a-week.