David Luiz appeared a step closer to becoming a Chelsea player on Thursday after Benfica went public for the first time about their negotiations with the Barclays Premier League champions.
Portuguese giants Benfica released a statement to their country's stock exchange confirming they had received an offer, reportedly worth Â£26million, from the Blues for their 23-year-old Brazil defender.
It read: "We have received an offer from Chelsea Football Club for the acquisition of the sporting and economic rights of David Luiz. A negotiation process between both parties is ongoing and the market will be informed when it is completed."
Chelsea have four days to reach an agreement with Benfica before the transfer window closes, which on paper is plenty of time.
However, they have been in and out of talks with the Portuguese champions for almost a month since seeing a reported £17million bid rebuffed at the end of December.
They were confident enough of concluding the transfer this week to apply for a work permit for Luiz, which was granted on Wednesday.
But proof the clubs were still haggling over the finer points of the deal arrived when the defender played the whole of his current side's Portuguese Cup win at Rio Ave on Wednesday night.
The dispute reportedly centres on the precise make-up of the deal, with Benfica unwilling to entertain the fee being paid in instalments.
They are also said to be cool on the idea of a player-plus-cash arrangement, with Nemanja Matic - currently on loan at Vitesse Arnhem - having been mentioned as a possible makeweight.
Luiz, whose contract at Benfica expires in 2015, is widely regarded as one of the most promising defenders in Europe.