Olympiakos defenders Paraskevas Antzas and Vassilis Torosidis are wanted by Rangers.
The Daily Record says one or both could be snapped up in the summer if reports continue to be favourable.
Antzas and Torosidis have been added to Walter Smith's list as he prepares to strengthen his squad. He watched 22-year-old Torosidis and his 31-year-old team-mate in Olympiakos' goalless Champions League draw with Chelsea in Athens on Tuesday.
It is understood the manager was impressed enough to continue keeping tabs on the pair.