One of Nadal's 'toughest' moments

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(CNN) -- Rafael Nadal battled for nearly six hours with Novak Djokovic at the 2012 Australian Open, the longest grand slam final in history.

Seemingly on the verge of exiting in the fourth set, Nadal rallied and then led by a break in the fifth before his Serbian opponent ultimately had the last word.

When the bruising slugfest was over, in an unusual move, the players were given chairs during the trophy presentation.

Nadal's loss to Stanislas Wawrinka this January in the Australian Open final featured a more routine looking scoreline and lasted a shade over two hours, so nowhere near as tiring -- but the world No. 1 says it was tougher to deal with than the reverse to Djokovic.

That's because Nadal hurt his back in the warm-up and wasn't able to compete at 100%.

The injury, coupled with Wawrinka's play, led to the Swiss claiming his first grand slam title. Nadal was the heavy favorite pre-match, owning a 12-0 head-to-head record without dropping a set.

"It was one of the toughest moments in my career," Nadal was quoted as saying by the ATP's website Thursday at the BNP Paribas Open. "It was tough being there for 90 minutes knowing that you will not win. But not winning was not the worst thing. The worst thing was knowing I could not compete.

"When you are losing and competing, that's part of sport. This loss was worse for me than 2012 and the six hours against Novak. I did everything right to be there and compete in the final, and I couldn't. Wawrinka was playing unbelievable. I don't know if I would have had the chance to win that match because he was playing amazing."

Nadal admitted it took a while for him to get the loss out of his system.

"I am a great loser," he said. "Normally after a few hours I forget about the losses and look straight to the next thing, but after this tournament it took a little bit more time."

The back still not recovered, Nadal skipped an event in Argentina last month but returned -- and won -- in Brazil.

He says the back is now "healthy," bad news for his opponents in the California desert.

It's Nadal's most successful hard-court Masters tournament, having won in Indian Wells three times and only failing to reach the semifinals once.

Last year Nadal triumphed not long after his comeback from a serious knee injury.

"It was one of my most special titles," he said.

Nadal faces a tricky draw, however, with Wawrinka, Roger Federer and Andy Murray in his half.

Azarenka uncertain

Meanwhile in the women's draw, two-time grand slam champion Victoria Azarenka played down her chances after only recently recovering from a foot injury. Azarenka was forced to wear a protective boot so the foot could heal.

"When you hear for the first time from the doctor, 'You've got to wear a boot for three weeks,' and the tournament is in four and a half weeks you're like, 'Okay, well, we'll see how it goes.'

"What I expect for myself is to fight for every ball. The rest is a little bit of an unknown for me right now.

"The first match is going to happen. I'm going to go out there and I'm going to play. The most important thing for me is that my foot feels good."

Azarenka -- a walkover in Indian Wells last year after retiring in 2011 -- begins against American Lauren Davis.

Read: Wawrinka ousts ailing Nadal

Read: Azarenka upset in Melbourne

Via: One of Nadal's 'toughest' moments