Should Walter Smith's side progress at the expense of the Portuguese they would face PSV Eindhoven or Fiorentina for a place in the final.
The first leg of the quarter-final will take place at Ibrox on Thursday 3 April, with the return leg in Lisbon seven days later.
Rangers chief executive Martin Bain said: "We have nothing to fear and it's all about enjoying it."
The Ibrox club secured their place in the last eight after defeating German outfit Werder Bremen 2-1 on aggregate.
And Bain said Rangers were confident of going further in the tournament.
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"Sporting are a club with a decent heritage and I'm sure Walter Smith will be taking them extremely seriously," he said.
"At this stage of the competition, all the teams are of a level, but we have had a good European campaign.
"We came up against the best team in the Champions League and narrowly missed out on qualification.
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