Nadal questioned his motivation after crashing out of the ATP World Tour Finals in London in November although he promptly displayed plenty of heart in helping Spain beat Argentina in the Davis Cup final in Seville.
The world number two has frequently tried to downplay his comments, claiming they were exaggerated, and he was quick to emphasize he was ready for battle in Melbourne with the tournament getting under way on Monday.
He said: "What I said was that I played a few matches at the end of the season with less passion than usual. That's nothing crazy. That happens when you are a little bit more tired than usual.
"I'm here in Australia with big motivation, with big passion. I have tried to enjoy the past few weeks, which I did, and I am happy.
"I am practicing well and enjoying everything. I will try to be ready for tomorrow [Monday]."
Nadal won the French Open and reached the final of Wimbledon and the US Open in 2011 but that was not enough to prevent him losing the world number one spot to Novak Djokovic, the all-conquering Serbian claiming three majors in a dominant 12 months.
And the Majorcan admits he has some catching up to do.
"Novak is the best because last year he did a fantastic year and is the number one," he said.
"He deserves to be there but I will fight every moment to try to compete with everybody to give myself a positive chance of victory.
"It's just the beginning of the season but I will try to improve on a few things."
Nadal has already announced he will take next month off to rest a nagging shoulder injury but he insisted he was in good shape heading into the season's opening grand slam event.
"I am just happy to be here to start another season in good condition," he said.
"I am healthy, that's the first thing and the most important thing. Without that you cannot think about the following things.
"I am healthy and ready to work hard."
Nadal plays his first-round clash with American qualifier Alex Kuznetsov on Monday with the pick of the opening day's matches the clash between home hope Bernard Tomic and experienced Spaniard Fernando Verdasco.
Tomic, 19, won the AAMI Kooyong Classic build-up event, beating world number eight Mardy Fish in the final, and is oozing self-belief.
He said: "I am ready to go. I have had a good preparation and built up some confidence over the past few weeks and I think it's going to be an exciting match on Monday.
"To play Kooyong and to have those matches under my belt and win them all is great.
"Confidence is key before a tournament like this and before playing a player like Fernando.
"He has one of the best forehands but if you keep the ball to his backhand corner he's not going to hurt you. That's what I am going to do tomorrow [Monday]."