India thrashed Australia [ Images ] 2-0, handing them their worst defeat in the last 22 years.
Warne believes Australia's champion aura was partly created by being ultra-aggressive and going for the jugular when Tests were on the line.
As Australia plummeted to their lowest ever Test ranking of fifth, Warne said Test rivals are gaining confidence because Australia sometimes shies away from their win-at-all-costs mantra.
He believes Australia are picking their best possible team, but says they must not go into their shell during big moments.
"Why aren't we converting strong positions into victories? We have to learn how to win again. The best way to learn to win is have a mindset where you have to attack. You have to be prepared to lose a Test to win a Test," he said.
"You always have to think 'how am I going to get this batsman out' - not just dry things up. I think India deserve to be the No.1 side in the world because they attack a lot and have got a lot of good variety," Warne added