The 26-12 victory came 11 years today over their only other victory in the Millennium Stadium, and it followed a promising - if winless - debut campaign in the Rugby Championship.
A magnificent second-half performance in Cardiff earned them victory over the Six Nations champions and Ayerza says it proves they are moving in the right direction.
"We didn't have control of the game in the first-half," Leicester prop Ayerza said. "The scrum and the line-out weren't going our way, but we came back into the game.
"Playing games against the best sides in the world and playing at a high tempo and intensity can only help us to develop.
"You saw that against Wales. We played 80 minutes at a very good intensity, and this win is massive for us.
"It shows we are going in the right direction and that we are improving as a nation. To beat Wales at the Millennium Stadium is a huge achievement, one that we are very proud of.
"This year has been our first season in the Rugby Championship, and there is no doubt we will continue to improve.
"Now, we have two more massive games coming up against France and Ireland. They will be tough, but this win will have given us extra confidence."
Skipper Juan Martin Fernandez Lobbe led from the front with a magnificent display - a fitting way to mark his 50th cap.
And Ayerza added: "He is such a talisman for us, such a positive influence in so many different ways.
"He is one of the best captains I have ever played under, and he always shows the way with his performances. He always gives 100%."
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