Cristiano Ronaldo bagged a hat-trick as Juve came from 2-0 down on aggregate to win 3-2 in Tuesday’s last-16 Champions League tie.
His third, from the penalty spot, came in the closing stages of the second leg and sparked wild celebrations among the Juventus players and fans.
And Ronaldo appeared to be venting plenty of frustrations at the away supporters, having previously played for their city rivals Real Madrid.
Ronaldo was picked up on Vamos de Movistar cameras, and Spanish lip-readers claim the 34-year-old was shouting “hijos de puta” (sons of b******).
The superstar could now face a ban from UEFA, especially when paired with his celebration.
The Juve star grabbed his crotch, like Atletico boss Diego Simeone did after the first leg.
Ronaldo appeared to aim his gesture at the travelling Atletico fans, something the La Liga club are believed to not be best pleased with.
Simeone was fined 20,000 euros (£17,000) for his gesture for improper conduct.
Ronaldo only left Real Madrid last summer, joining Juventus in a £105million deal.
And having shone in Tuesday’s Champions League encounter, the Portuguese ace insisted that was why the Serie A giants signed him.
Ronaldo Sky Sport Italia: “It had to be a really special night and it was.
“If we continue like this, we have not won yet but we have reasons to be proud and we are on the right way.
“That’s why Juve signed me and I tried to do my best job.
“It’s a magical night. It was a very difficult team to play but we showed that we were a very big team.
“We proceed step by step, we will see.”
Juventus will face Ajax in the quarter-finals of the Champions League.
Should they win that, they will come up against Manchester City or Tottenham in the semi-finals.
A return to England therefore beckons for Ronaldo.