Rangers say they are taking legal advice after a scheduled friendly was cancelled.
The Ibrox club were due to fly to Canada on Tuesday to face Benfica in the Eusebio Cup three days later.
But in a statement on Saturday night, Rangers said Benfica had pulled out.
"Rangers were due to fly out to Canada for the match -- scheduled for Tim Hortons Field in Hamilton -- on Tuesday 3 October but were informed of Benfica's decision only hours ago," the statement read.
"The organisers, Elite Soccer Entertainment, have apologised but Rangers will be expressing their displeasure on behalf of themselves and their supporters in the strongest possible terms.
"Rangers also wish to apologise to those fans who had made arrangements to travel, and those in Canada who were looking forward to the match.
"Rangers will take legal advice before commenting further."