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The Spaniard suffered a second successive reverse in Sydney, going down 3-6 6-1 7-5 to Alex de Minaur after falling to Cameron Norrie.
Nadal is set to go in search of a record-extending 23rd grand slam title later this month, having won in Melbourne in 2022.
De Minaur deals Nadal another huge upset
Yet the 36-year-old is not getting hung up on his form, instead taking the losses as learning curves.
"I have two weeks before the Australian Open starts," he said. "I can't say the situation is ideal, but I can't say it's negative.
"I was playing good. I need hours on court, I need battles like this. Days like these two help. I need to keeping fighting.
"I'm not too alarmed, too negative about what happened. I think it was a real chance to lose these kinds of matches."
Nadal won the first set against De Minaur, and was a game away from victory in the decider before succumbing to a comeback.
"Alex played better in the crucial moments. That made the difference," Nadal said.
"I had my chances to win, but I made costly mistakes when I could not afford them. You can not win a match like this while doing that."