Los Blancos have won the European Cup in each of the last three years, with Ronaldo scoring 43 times in the competition since the start of the 2015-16 campaign.
The Portugal international managed 450 goals in total for the capital giants before joining Juventus this summer, but former Barcelona defender Alves has insisted that Madrid are still a serious threat in Europe.
"I think that, contrary to what everybody thinks, Madrid is more of a team without Cristiano," Marca quotes Alves as saying.
"Now it's a bit more difficult than it was before, before it was complicated for the opposition but focused a lot on Cristiano, and now it's a bit more dangerous, at least because of how I see football and my concept of the game.
"Madrid are more of a team now, it is obvious that Cristiano is a brutal loss for Madrid, but Madrid are Madrid."
Ronaldo opened his goalscoring account for Juventus with a brace in their 2-1 win over Sassuolo at the weekend.