The Europa League champions will face Real Madrid in Cardiff for the UEFA Super Cup early next week, and they are desperate for their youngster to use it as his swansong for the club.
Liverpool are understood to have agreed a £14m fee for the left-back, with personal terms also settled.
Midfield starlet Suso may head in the opposite direction for the coming season as part of the arrangement, where he would link up with fellow Reds loanee Iago Aspas.
Brendan Rodgers’ capture of the full-back is likely to see his transfer plans near their close, with over £100m spent on eight first-teamers.
A replacement of Luis Suarez could be the final act, with Liverpool thought to be tracking unwanted PSG attacker Ezequiel Lavezzi.
Marco Reus or Dortmund is another rumoured target, while Wilfried Bony has been on their radar in recent months.