Maria Sharapova survived a scare, too, while Roger Federer might have been stung by a bee on an eventful third day at the year's opening major.
Hampered by knee, hamstring and back injuries in past losses in Melbourne, 14-time grand slam winner Nadal felt dizzy and was close to exiting in the second round against American qualifier Tim Smyczek. But Nadal showed his champion's heart to rally past his 112th-ranked foe 6-2 3-6 6-7 (2) 6-3 7-5 in more than four hours.
When the night match was over Nadal sunk to the court, reminiscent of a celebration for someone who has just won a grand slam final.
In an on-court interview, he said cramps were the source of his troubles. Recent inactivity didn't help, either. Nadal hasn't played much tennis the past six months.
"I felt very tired after the first set," Nadal told the crowd.
"I don't know what's going on," he added. "I felt this irritation after the first set.
"I started to have some cramps around the body, different places, so that says I was not in the perfect shape because it's not normal after one hour to start to have these types of things. But it's normal, after a tough period of time without having the chance to be on the tour."
The last time Nadal played under the lights on Rod Laver Arena, it was indeed in a grand slam final. He hurt his back 12 months ago
and lost to Stan Wawrinka in four sets.
There didn't appear to be anything amiss with Nadal after he won the first set in routine fashion against Smyczek on Wednesday, but things took a turn for the worse for him in the middle of the second.
Recovering a break for 1-2 in the third, Nadal called for the doctor and was given medication.
Nadal's shots lacking depth from the baseline and with no punch on his serve, Smyczek grew in confidence. Still when Nadal broke and held for 5-3, order seemed to be restored.
Smyczek, though, broke back and swept to the tiebreak 7-2 with some flashy tennis.
Early in the fourth, a hunched-over Nadal was spent physically but somehow he broke and closed out the set.
Holding a 16-5 record in fifth sets, the numbers favored Nadal in the decider. Despite missing three break points earlier in the set, Nadal capitalized in the 11th game and eventually prevailed.
But Smyczek walked off court to huge applause. If his winners weren't enough, he allowed Nadal to replay a serve in the last game when a fan shouted out. Nadal took note.
"Not a lot of people would do something like this at 6-5 after four hours, so just congratulate him for that and because he played a great match," said Nadal.
Sharapova close to exiting
It was the second round of the Australian Open, so Sharapova should have known there would be some drama.
A year after the Russian saw off Karin Knapp 10-8 in the third set in sizzling conditions in Melbourne, she was even closer to exiting Wednesday.
Sharapova needed to save two match points before finally overcoming compatriot Alexandra Panova 6-1 4-6 7-5 in similarly steamy -- though it wasn't as warm as last year -- daytime conditions.
Sharapova struck 43 unforced errors in the final two sets but crucially for the five-time grand slam champion, she produced forehand winners on the match points with Panova serving at 5-4 in the third.
That game was a missed opportunity for the 150th-ranked qualifier, and Panova also led by two breaks in the third at 4-1.
Sharapova, who is attempting to win a first major in seven years outside Roland Garros, was left both relieved and annoyed.
"I didn't feel that I was positive enough, even though I was making a few more errors than I would have liked," she told reporters. "And I wasn't making enough first serves.
"But I was thinking about it too much instead of just like being in the present, saying, 'Hey, go up to the line, do what you do, do what you've done thousands of times.
"I'm good at that and I'll continue to be good at that. But some days are just a little off. Today was one of them."
Sharapova's performance might not bode well for the rest of the tournament, but at the same time, it might simply be a blip.
Last year at the Australian Open, Li Na survived a match point in the third round against Lucie Safarova and then went on to win her second grand slam title.
"You never know how you're going to feel until you go out on the court and compete and play," Sharapova said. "No matter how you prepare, what you did, once you get out there, everything starts from scratch.
"It was a tough day, but I pulled through. I guess at this point that's what matters.
"Certainly gives me a lot of confidence that I didn't play my best tennis and was able to come through."
Federer drops set
Federer lost a set and was visited by the trainer, too, although he wasn't troubled nearly as much as Sharapova and Nadal.
He called for the trainer after losing the first set due to an issue with his hand, yet wasn't sure what the problem was.
He didn't discount a bee sting.
"I don't know what it was," Federer said. "I still don't know. I just wanted to have a chat with the physio just see what we can do.
"I know there is nothing we could do. I knew we couldn't tape it up because then it would be even bigger and more weird. I just said, 'I hope it doesn't get worse or stay like this.' Actually it went away, but now I feel it again."
The record 17-time grand slam winner recovered and eventually eased past Italian Simone Bolelli 3-6 6-3 6-2 6-2. Federer only faced one break point and hit 15 aces.
The Swiss' potential quarterfinal foe is Andy Murray, and the Scot made quick work of Aussie Marinko Matosevic 6-1 6-3 6-2.
Viktor Troicki, meanwhile, extended his winning streak to 10 matches by defeating Argentina's Leonardo Mayer 6-4 4-6 6-4 6-0.
The Serb's ranking fell outside the top 800 in July following a contentious drug suspension but Troicki now finds himself in the top 60 after winning a title in Sydney last week. The ranking will climb further with his wins in Melbourne.
"I'm enjoying playing tennis and having fun on the court," Troicki, a former top-20 player, said. "I missed it a lot and that gives me a lot of joy on the court and a lot of motivation.
"Trying to use any chance, any match, any tournament. It's going well."