A VAR review denied Juve a fourth-minute opener, but Ronaldo's first header of the game gave them hope and the Serie A leaders drew level in the tie thanks to the Portugal superstar's aerial power again.
Ronaldo, jeered almost every time he touched the ball, had a quiet performance in his first match in the Spanish capital since leaving Real Madrid last summer.
Atletico coach Diego Simeone has chosen a 4-4-2 formation with defender Diego Godin returning from injury while forward Alvaro Morata starts alongside Antoine Griezmann instead of suspended Diego Costa. Let us know in the comments section below. "It was a great result, scoring twice and not conceding, but we will have to be prepared for the final 90 minutes in Turin".
Ronaldo nearly scored when his long-range free kick forced Atletico goalkeeper Jan Oblak to make a hard save in the ninth minute.
That miss was punished four minutes after the restart when goal-line technology ruled Oblak failed to keep out another Ronaldo header, Joao Cancelo this time providing the cross.
Can Ronaldo steer Juventus to European glory?
CR7 has scored 22 goals in 32 career games against Atleti, constantly a thorn in the side of Los Rojiblancos.
The Portugal worldwide forward's goals took the Bianconeri into the quarterfinals and kept him in the hunt for a sixth Champions League title - a fourth in a row - and he reflected on a "magic" night.
However, Juventus also must defend with supreme commitment and focus, as one Atletico Madrid goal will require the Italian club to score at least four goals to advance.
Juventus was runner-up in the Champions League in 2015 and 2017. The home fans erupted on the final whistle and the players rushed to Ronaldo.