Muller scored from the spot in the 11th minute, before Mats Hummels doubled the lead with a thumping header from a corner.
Read how the action unfolded below.
Germany: Weidenfeller, Zieler, Ginter, Durm, Mustafi, Grosskreutz, Kramer, Schweinsteiger, Draxler, Schurrle, Podolski, Klose
Portugal: Eduardo, Beto, A Almeida, Neto, Costa, Carvalho, Vierinha, Silva, Varela, Amorim, Postiga, Eder
Germany scored the most goals in qualification (36) but only 1 goal (Per Mertesacker vs Faroes) was from a set piece. pic.twitter.com/Xq6iYTliSf— MatchStory (@MatchStory) June 16, 2014