Ventura's side are unbeaten in their last nine matches after Wednesday's 3-0 friendly win over Uruguay in Nice.
They are expected to extend that to 10 games when they host Liechtenstein in a qualifier in Udine on Sunday, a game they need to win to ensure they stay in touch with Spain.
Both sides are locked on 13 points after five games in Group G, meaning September's clash in Madrid is likely to determine who qualifies automatically for Russia 2018.
Following their latest success, Ventura said he was pleased with the progress his side have made and backed them to upset the former world champions later this year.
"Some of the objectives we had set are slowly getting achieved," he told Rai Sport. "The most important thing [against Uruguay] was the mentality, as usually Italy friendlies are never good.
"We had the right approach, didn't allow a chance on our goal, had six or seven chances and played with a certain degree of sharpness.
"There's a lot to be done, unfortunately there isn't much time to do it in, but I am happy. It's difficult to make football this organised in such a short space of time.
"I've been in football for many years, so I know that big statements and promises mean little, you have to know who you are and prove it every time.
"We've got the chance to become something important in the future."
Substitute Eder scored late on at the Allianz Riviera after Jose Gimenez's early own goal had put Italy ahead, with Daniele De Rossi's stoppage-time penalty wrapping up the win.
Inter forward Eder shares his coach's confidence ahead of the Spain clash, but knows they must not take Liechtenstein for granted.
"The coach believes, and we believe, that we can do well in Spain," he said. "The coach has kept some important veterans and introduced very good young players [to the squad].
"Nothing is to be taken for granted. We are working to be in the best shape for Liechtenstein, which is the game that matters the most."