Rangers knew that the trip to face Olympiacos was going to be a tough assignment against a team that were Europa Conference League winners last season. On that run, they disposed of Unai Emery’s Aston Villa in the semi-finals, proving the size of task faced by Philippe Clement and his squad. The manager would have been able to review the footage from the friendly at Ibrox between the two sides, and Gelson Martins is the type of player who Rangers needed to pay close attention to. READ MORE: The eight games Rangers play straight after each Europa League league phase clashDujon Sterling shows wh…