The clash between Italian giants Inter – winner of 18 Serie A titles and three-time champions in Europe's second-tier competition – and Iceland's Stjarnan is the feature tie of the Europa League's play-offs.
Stjarnan host the first leg on Wednesday and, with a spot in the group stages up for grabs, the stakes could not be higher for a side who have negotiated a way past Bangor City, Motherwell and Lech Poznan so far.
Inter are yet to play a competitive game this season and were far from their best in an uninspiring 0-0 friendly draw with PAOK last week.
And Sigmundsson is hoping to take advantage of Inter's lack of match practice.
"We know their weaknesses," Sigmundsson said.
"We are ready for the game, we're in good shape and arrive with the right mentality to fight.
"We tried to analyse Inter and their style of play, but obviously tomorrow we go beyond recordings.
"Our objective is to get a result. Inter aren't at their best yet and we have to face them with an intelligent approach.
"Inter are certainly the strongest opponents we have ever faced, but we know their strengths and their weaknesses."
Inter could hand competitive debuts to Nemanja Vidic and Pablo Daniel Osvaldo in the clash.
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