While Wozniacki is the current WTA Finals champion in women's singles, she remains in search of her first ever Grand Slam singles title. Whereas, women's No. 1 Simona Halep took a longer route - equaling a mark in Melbourne for endurance.
In both her first two matches, Davis lost the first set but came back to win the next two - and the matches - in emphatic fashion.
South Korean Chung Hyeon does not appear especially intimidating behind his Zen-like demeanour and white-framed spectacles but as German wunderkind Alex Zverev will testify, the 21-year-old should come with a health warning. "But at 13-all when I took the game, I said it's my lucky number".
Davis, a baby-faced 24-year-old with a monster forehand, was majestic in defeat, breaking Halep three times when the Romanian served for the match and battling on after losing a toenail late in the game. Because I didn't really feel any pressure or anything.
Sharapova said Kerber was the more aggressive on court, and took more risks.
She continued: "That third set was nothing really like I had ever played before, such an awesome atmosphere. She's an incredible player", Davis said.
"There's a lot of Voltaren and painkillers in her system". "Today was not enough (but). looking at the overall picture, there's a lot to build from".
Davis, who had three match points at 11-10 in the final set, having prevented Halep from serving it out on three occasions, was exhausted but still upbeat post-match.
Davis crept through service games for 12-11 and 13-12, but her energy deserted her in the next as Halep broke through again, this time holding serve to wrap up victory in three hours and 47 minutes.
"I never played a third set so long. I think my second toes are just a bit infected", she said. My ankle, I don't know how it is because I don't feel it any more.
Keys, who missed last year's Australian Open after undergoing surgery on her injured left wrist, will next play the victor of Saturday's match between Aliaksandra Sasnovich and No. 8 seed Caroline Garcia.
Keys advanced 6-3, 6-4 over Ana Bogdan and will next play No. 8 Caroline Garcia, who beat Aliaksandra Sasnovich 6-3, 5-7, 6-2.
"Lindsay is incredible. We've had three years together and she has taught me how to handle big moments like this", said Keys, who made the Australian Open semis in 2015. The 17th-seeded Kyrgios won the last five points after falling behind 5-2 in the tiebreaker.
The questions about world No. 1 Simona Halep's injured ankle will have to be answered another day.
No. 23 Gilles Muller outlasted Malek Jaziri in five sets, Kyle Edmund had a straight-sets win over Denis Istomin - who beat then defending-champion Novak Djokovic in the second round here previous year - and No. 28 Damir Dzumhur beat John Millman.
"That was insane", Wozniacki said after winning the last six games in a memorable 3-6, 6-2, 7-5 victory.