Wozniacki, trying her best to convince everyone she's a worthy No. 1, faced an opponent who gave her all sorts of problems the last time they met. Henin had to contend with chilly, windy conditions, not the best environment for an elbow that remains less than 100 percent. When will the summer arrive in Melbourne?
In the end, both advanced easily, and at roughly the same time.
First to Wozniacki.
The Dane needed to rally against California's Vania King at Indian Wells in March, trailing 4-1 in the third. No such problems for Wozniacki this time, and she cruised 6-1, 6-0.
As she made the U.S. Open final two years ago, Wozniacki struggled to hit more winners than unforced errors, even in registering some destructive results. Retrieving and keeping the errors down did the job.
The stats versus King -- 23 winners and only eight unforced errors -- produced a nice reading for Wozniacki's adviser at adidas, Sven Groeneveld, a stickler for numbers. Still, he discussed the first round a tad, when Wozniacki toiled for nearly two hours in a straight-sets victory over Gisela Dulko.
"I was actually hoping that she would settle into it a bit," said Groeneveld, quite the calming presence. "She didn't settle into it as I expected."
"Yes, but still, Caroline should be able to get to a level that's quite comfortable," he said. "She didn't really seem to be comfortable."
Wozniacki must have been a dream to coach in her formative tennis years. She plays the percentages, not trying to be too fine, and possesses a tennis brain. Yet when it comes to crunch time against the elite, she needs to think outside the box. Her baseline play leads to some predictable patterns, which Groeneveld acknowledged.
Groeneveld compared the 20-year-old to Rafael Nadal. Nadal essentially began his career as a counterpuncher, but now he's so much more. Wozniacki's serve and forehand, he assured, could get bigger.
"The speed of serve did improve today," Groeneveld said.
It needs to work Friday, when Wozniacki battles frequent foe Dominika Cibulkova. Cibulkova fell to Wozniacki in the U.S. Open quarterfinals in September before prevailing last week in Sydney's first round.
"I had some good practices after Sydney and am feeling good here," Wozniacki told reporters. "I've been feeling confident and comfortable on the court."
Henin, the owner of seven Grand Slam titles, seven more than Wozniacki, appeared far from comfortable in the first round against Sania Mirza. Mirza bludgeoned forehands in the first set, leading to a look of concern on Henin's face. Henin peered at coach Carlos Rodriguez, as usual, but atypically got mad at her team in the stands. Mirza dipped, and Henin advanced in three.
In confronting breakthrough Brit Elena Baltacha, the Belgian got a similar opponent, although not as good. Henin had joy moving Baltacha around, making sure to get the first strike, and was impenetrable on serve.
Henin changed her serve prior to her comeback in 2010, tossing the ball further into the court for more oomph, with mixed results. Against Baltacha, she didn't get broken and won 84 percent of first-serve points. Other parts of her game didn't need to exceed second gear.
"It was the worst conditions, to play the first match and in this temperature," Henin told reporters. "The weather didn't help. But I have to deal with it and get ready. I did a good job."
Henin ground out victories en route to the 2010 final, where she finally was stopped by, who else, Serena Williams. Henin's next foe is two-time Grand Slam champion Svetlana Kuznetsova, who could extend her, despite being 2-16 in their head-to-heads. The slumping Russian, with a new coach, again, is the kind of player who can beat anyone in the right mood.
"I think Henin will take the concentration up a notch," said Belgian Filip Dewulf, a French Open semifinalist in 1997. "I think she'll grow into the tournament like she did before. Maybe she hasn't hit that 100 or 120 percent, but she's still good enough to go far in the tournament, maybe all the way."
Henin can take her varied game to another level. With Wozniacki, at this point, no one is sure.
Ravi Ubha is a frequent contributor to ESPN.com.