IT was the day that carnage was wreaked on Australian Open singles draws.
But at 1.37am on Wednesday morning (EDT), which had technically turned Day 9 into Day 10, Caroline Wozniacki brought back a sense of calm and normality back to this most calamitous of grand slams.
Not that there wasn't a late night wobble.
The world No. 2 advanced to just her third major semi-final since 2011 with a 6-0 6-7 (3-7) 6-2 win over Spain's Carla Suarez Navarro on Rod Laver Arena.
Forced to start close to 11.30pm (EDT) following the men's epic between Marin Cilic and Rafael Nadal, Wozniacki appeared to be a woman in a hurry to get back to the hotel as she took the opening set in just 34 minutes.
Suarez Navarro started to turn the match on its head in the second set, shooting out to a 4-2 lead, before Wozniacki looked to have regained her composure - setting up a match point at 5-4 up on the Spaniard's serve.
But, true to the day's drama, Suarez Navarro saved it and then rode that momentum into the tiebreak to take this match into the most unlikely of deciders.
Not that the hiccup would prove fatal for Wozniacki.
Really it only served to keep her out of bed not to mention the few thousand hearty souls that remained in the stands for an extra 45 minutes.
Wozniacki will play Elise Mertens in the semis, the Belgian world No. 37 taking out No. 4 seed Elina Svitolina 6-4 6-0 earlier in the day.
Mertens' triumph would be the first of a string of three quarterfinal singles upsets, with Kyle Edmund taking out Grigor Dimitrov and Cilic overcoming Nadal - with the little help of an unfortunate injury - in the men's draw.
But Wozniacki, eventually, was having none of it.
"I knew it wasn't going to be that easy (for the whole match), a lot of the games we played in the first set were very close and I got lucky, as well, guessing right on some break points," Wozniacki said.
"In the second set I had the chance to close it out and I couldn't do it, which I was very disappointed about. But I was proud that I was able to stay cool and finish it off.
"She improved, she took the ball earlier, she made me step back behind the baseline a little bit and that made the difference.
"I stepped a little closer to the baseline in the third set and then felt like I had a little bit more energy left than she did."
Wozniacki's resurgence is nearing a triumphant completion.
The former world No. 1 has never won a grand slam, twice losing US Open finals - in 2009 and 2014. However, TAB has her as the new favourite just ahead of Angelique Kerber.
This equals her best Australian Open run, mirroring her final four appearance in 2011.
The second seed will now be considered tough to beat as she seeks a breakthrough major, with the 27-year-old seemingly playing with greater freedom after fighting off match points in her round two clash with Croatian Jana Fett.
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