Die Mannschaft take on Paulo Bento's men on June 16 before fixtures against Ghana and USA in a tough-looking Group G.
"Portugal are a great team and Cristiano's a fantastic player, but we've got the players and methods to stop him," the 54-year-old told reporters.
Low also explained his side's decision to play Armenia in their final warm-up match before the World Cup, as well as giving some team news ahead of the fixture.
"We deliberately chose to play Armenia as they play a similar counter-attacking style to Portugal," he added.
"Roman Weidenfeller will be playing. Manuel Neuer will not play ... but he will be fit to face Portugal in Brazil."
"[Philipp] Lahm and [Bastian] Schweinsteiger will be given some playing time. Both have trained individually over the last few days."