At the Estádio da Luz in Lisbon, Ronaldo surprisingly appeared outside of coach Roberto Martínez's starting eleven for the second-round match, but he still proved decisive by completing the Portuguese comeback in the 88th minute, after having been brought on at the start of the second half.
The 'formula' was the same as that used against Croatia, with Nuno Mendes crossing from the left and Ronaldo tapping it in.
Before that, after just four minutes, McTominay gave Scotland the lead, with Bruno Fernandes equalising in the 54th minute and starting the Portuguese team's comeback.
Portugal ended up winning deservedly, given the large number of opportunities they created throughout the match, against a Scotland that fought hard and made life very difficult for the Portuguese team.
After the first two rounds, the Portuguese team has only won and is now the sole leader of group A1, as Poland was beaten by Croatia (1-0), and is now sharing second place with the Croatians. Scotland is still on zero points.