The 33-year-old was one of the first players that Glasgow Rangers boss Mark Warburton brought to Ibrox this summer.
Tottenham Hotspur boss Mauricio Pochettino has been impressed with Will Miller and Marcus Edwards.
The Bhoys are favourites to progress following Wednesday's first leg draw.
The midfielder is one of seven new signings at Anfield this summer.
Chelsea goalkeeper Asmir Begovic is reportedly on Crystal Palace's radar.
Stewart could be next out of Dens Park, with Gary Rowett's team said to be circling.
Jordan Botaka has struggled to make an impact at Leeds United.
The Bayern ace says Gundogan is comparable to some of Spain's top stars.
The former Arsenal man believes Ronald Koeman could get the best out of him.
The Scottish Premiership side secured a promising 1-1 draw from the game in Kazakhstan.