Thomas Müller hit a hat-trick and Mats Hummels also got on the scoresheet in the three-times winners' Group G opening stroll against the 10-man Portuguese.
Merkel posed for a selfie with Lukas Podolski in the changing room
And Merkel, who watched the game alongside Fifa president Sepp Blatter, personally congratulated the players in the Arena Fonte dressing room.
Prolific on social media, Lukas Podolski inevitably got a selfie with the chancellor.
Germany's victorious squad pose with Merkel after their 4-0 win against Portugal