Forty thousand were on their feet and slowly they started to applaud. Just a ripple at first but it quickly gathered force until acquiring the status of a fully-fledged standing ovation.
The Italians were not happy to be on the receiving end of a breath-taking moment of athletic brilliance yet they were prepared to acknowledge a genius at work.
Such moments are rare in a sport of tribes and such is the effect of Cristiano Ronaldo.
The crowd in Turin held its collective breath as he took off, springing high into the air, twisting his body with his back to goal as he tracked the arc of a cross from Dani Carvajal.
Everyone knew the discipline he was about to attempt came with an extreme degree of difficulty.
Yet few doubted him. Sure enough, Ronaldo delivered. He always does. The bigger the stage the better as far as he is concerned.
His body uncoiled, his muscles were unleashed, his timing was perfect and an exquisite scissor-kick flashed past the frozen figure of Gigi Buffon.
The ball nestled into the net, and Real Madrid were 2-0 up away from home, well on their way to the last four of a competition they have won for the last two years.
Juventus, conquerors of Tottenham in the last round, were staring at the Euro exit and still their fans stood generously in recognition for one of the great players; perhaps, too, one of the great Champions League goals.
It was certainly one worthy of comparison to the famous volley scored by his manager Zinedine Zidane against Bayer Leverkusen to win the trophy in 2002.
‘I played here and I know how good the fans are,’ said Zidane. ‘It is a great thing for the sport. It was a spectacular goal and I take my hat off to him.
‘The Leverkusen goal was beautiful, but the most important goal is the last one. Only Ronaldo can score this type of goal.
‘It is one of the most beautiful goals in the history of the game. I can’t say it is better than 2002.’
Ronaldo, having already scored the opener, basked in the acclaim and a clatter of records.
He is the first to score in 10 successive Champions League games, a sequence started in last year’s final against Juventus.
Since then, he has been on target in all six group games and both legs of the last-16 tie against Paris Saint-Germain.
From Cardiff to Turin he has led Real Madrid in pursuit of another European title, one which would take his personal record to five, level with four others and one behind Paco Gento on six.
Do not discount it. He is 33 but Ronaldo is getting better, certainly more influential.
His first came within three minutes, a vital away goal and it pressurised Juventus.
Ronaldo has refined his game since maturing into his thirties.
He is more of a striker than a prancing winger but the turbo boost is there and his first of the night came with such an injection of pace.
Ronaldo eased ahead of the centre-halves and stabbed at Isco’s low cross with the outside of his right foot, sending the ball whistling past Buffon.
His form in this high-class competition is staggering. So, too, his recent overall strike rate. He has scored 23 in a dozen games for Real Madrid.
Throw in a couple of headers against Egypt which turned a friendly in Portugal’s favour in stoppage time, during the international break, if you wish.
Ronaldo has mastered the art of influencing games at the elite level.
His second will live long in the memory and knocked the fight from Juventus, who were soon reduced to 10 men when Paulo Dybala was sent off for a second yellow card.
The first was shown for a dive just before half-time, a sign of desperation creeping in after chances had been squandered.
Marcelo stormed forward from left-back to knock in the third and Juventus were beaten for the first time since November.
Sergio Ramos will miss the return after a booking but the second leg is little more than a formality.
Real stride on towards the hat-trick and Ronaldo gets better with age, mature beyond all the pouting and posturing and simply a privilege to watch.
No matter who you want to win.
‘He is the most important player in the world,’ said Allegri. ‘It was an extraordinary goal and when you see this type of goal you can only applaud it.’
