"You play without a centre-forward because - it was the case last year, it is the case in the French team and it will be the case at Real, I have been killing myself saying it for months - Mbappe is not and will never be a number 9," Riolo said on After Foot. "Just like everyone else is a prisoner of this thing, Ancelotti is in the same prison.
"I'm going to repeat a sentence that I've repeated 150 times: Mbappe, either it's on the left, or it's on the bench. And on the left, there's better than him at the moment since Vinicius has the privilege of seniority and performances, so it's going to go to the bench because it can't be otherwise.
"He's not a 9, there's one on the bench (Rodrygo) and he's going to have to be played. Can Ancelotti take responsibility for such a decision? Real are a big club and capable of taking responsibility for such a decision but they can't continue like this, it's obvious."
Riolo continued by saying Real Madrid's current cycle could be over if they're unable to find a resolution to the issue.
"If they don't manage to do it by putting Rodrygo in, taking Mbappe out to find a team built in a similar way to last year, it will mean that we are at the end of a cycle," he added. "Which wouldn't be too serious because it happens in the history of clubs.
"When you are full of victories, when you have won so many Champions Leagues, all these players have had so much success, it happens to be supplanted by others who have the right to work well. It wouldn't be bad to see Barca or Liverpool better. But before arriving at this conclusion, Ancelotti will have to ask himself: what am I doing? Because he is doing things that are not normal at the moment."