Chiellini believes Italy reached "a turning point" in Cesare Prandelli's reign with their victory in Slovenia.
"We knew this was a turning point in our growth and improvement. We realised that the friendly with Germany was a huge boost in confidence and showed us what we can do," he said of last night's 1-0 win in Ljubljana.
"Now we have to keep working and developing, as this is a good side. This victory is a crucial stepping stone, as we kept a clean sheet and didn't run many risks, plus at this stage only we can throw away qualification. I doubt that will happen."