The Spanish veteran could complete a switch to the Estadio da Luz later in the week after dropping down the Yellow Submarine's pecking order
The 33-year-old left-back has been linked with replacing Fabio Coentrao, who joined Real Madrid in a €30 million move earlier in the summer, on the left side of Benfica's defence.
Horacio Gaggioli, Capdevila's agent, explained on Sunday the Portuguese club as 'an interesting option' for his charge, but refused to give out details only saying his client could leave the Spanish club on a free transfer.
Sources close to the negotiations have now told news agency EFE that the two clubs are locked in talks and the completion of the transfer 'is just a matter of days'.
It is thought Benfica want to formally present Capdevila together with Eduardo and Emerson, who are both close to joining the club from Genoa and Lille, respectively.
Capdevila, an international for Spain, has been an instrumental figure at Villarreal since his arrival in 2007, but he lost his place in the starting XI to Jose Catala towards the latter stages of the last season.