Cristiano Ronaldo said his superb hat-trick against Atletico Madrid to send Juventus into the quarter-finals of the Champions League is why the club bought him.

Ronaldo has won the Champions League four times in the past five seasons with Real Madrid but joined Juve in a deal worth €112million ahead of the 2018-19 season.

The Portugal superstar only scored once in the group stage, while he was also sent off against Valencia, but delivered in style to complete a stunning comeback against Atletico on Tuesday.

Diego Simeone's side led 2-0 thanks to goals from defenders Jose Gimenez and Diego Godin in the first leg but they crumbled in the face of Ronaldo's unstoppable aerial power in the return fixture.

Federico Bernardeschi's inswinging cross from the left wing found Ronaldo towering above Juanfran for the opener, the striker then levelling the tie on aggregate from Joao Cancelo's centre.

And when Bernardeschi's solo run was illegally halted by substitute Angel Correa, Ronaldo completed his record-equalling eighth Champions League hat-trick from the penalty spot to down Atletico yet again.

"This is why Juve brought me in, to help on magic nights like this," Ronaldo told Sky Sport Italia after knocking Atletico out for the fifth time.

"Atleti are a really tough team to face, but we are strong too and proved we deserved to go through. It's too early to talk about the final, let's take it one step at a time."

At a febrile Allianz Stadium, Ronaldo's treble ensured Juve overturned a 2-0 deficit to progress in the Champions League for the first time.

"It had to be a special night and it was," Ronaldo said. "Not just for the goals, but for the team and their incredible attitude.

"This is the mentality you need in the Champions League and we are on the right track."