Ronaldo nearly scored when his long-range free kick forced Atletico goalkeeper Jan Oblak to make a hard save in the ninth minute. Juventus enters the game trailing 2-0 and probably needs Ronaldo to continue terrorizing Atletico Madrid in order to advance.
While one ecstatic fan said: "CRISTIANO RONALDO".
There was no need to refer to VAR when Juve next had the ball in the net through Ronaldo's first header past the Slovenian keeper.
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. He had another attempt with a deflected shot a few minutes later, but didn't come close to the Atletico goal again until a late header sailed over the crossbar.More news: Serena Williams retires from Indiana Wells match
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"Anything could happen in the Champions League, a lot will depend on how we start the game", the Spain worldwide said.
Ronaldo had not played in Madrid since joining Juventus in a blockbuster transfer at the end of last season.
Sergio Aguero kicked off proceedings with two goals inside four minutes midway through the first half before Leroy Sane, Raheem Sterling, Bernado Silva, Phil Foden and Gabriel Jesus added to the onslaught. It resulted in a clumsy clip of the heels by Angel Correa in the Atletico box, a challenge typical of a forward trying to dig in and defend, the outcome never in doubt.
Juventus have progressed in a Champions League knockout tie having lost the first leg for the first time since 2005-06 v Werder Bremen.