The 31-year-old agreed a new one-year deal with Carlos Carvalhal's side.
The winger has previously enjoyed success in the second tier.
The goalkeeper joined Liverpool this summer in a move from Mainz.
The 30-year-old is currently out of contract with the Scottish Premiership side.
The Liverpool defender is free to resume his footballing career after the drugs ban was dropped.
Mark Warburton's Glasgow Rangers side are preparing for their return to the top flight after several years away.
Jurgen Klopp is reportedly planning to loan Ante Coric to Mainz if he joins Liverpool after July 21st.
Rangers have signed a number of new players this summer.
Aston Villa have signed Italian goalkeeper Pierluigi Gollini.
Arsenal midfielder Aaron Ramsey has suggested that there may be several stars struggling to be ready for the Premier League opener with Liverpool.