The 59-year-old pop star and her 12-year-old boy watched on from the Estadio da Luz in Lisbon - where they now live - as the home side beat Switzerland 2-0 to qualify for next summer's World Cup in Russia.
Madonna posted a selfie of the pair enjoying some mother-son bonding time at the match, and she added the caption: "Portugal Slaaaaaaaaaayyyyssssssssss! 2-0!!!! (sic)"
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The 'Like a Prayer' hitmaker and the youngster both wore Portugal scarves for the game, and he had a replica shirt on with Cristiano Ronaldo's name and number seven on the back.
David should get used to being in the stadium with a football shirt on as it is the home of Portuguese football team Benfica, whose youth academy he recently joined.
Madonna - who also has kids, Lourdes, 20, Rocco, 16, Mercy, 11, and four-year-old twins Stella and Esther - recently admitted she wanted to make the move to Lisbon to experience a new culture.
She said: "It's an experiment. I wanted to just go and experience another culture, music and art scene, and this one is phenomenal."
The Queen of Pop also admitted the sun-soaked country has left her feeling "very creative and alive".
She wrote on Instagram: "The energy of Portugal is so inspiring. I feel very creative and alive here. And I look forward to working on my film LOVED and making New Music!!! This will be the next Chapter in My Book! It's time to conquer the world from a different vantage point!! (sic)."