The Chinese No 27 seed produced the biggest shock result of the tournament so far after knocking the American out with a 6-4, 6-7 (2-7), 7-5 victory on Rod Laver Arena.
The victory comes just four months after Wang lost 6-1 6-0 to Williams at the US Open.
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It also means Williams’ wait for a record-equalling 24th Grand Slam singles title goes on, and the 38-year-old was honest in her assessment after the match.

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“She served well. I didn’t return like Serena. Honestly, if we’re just honest with ourselves, it’s all on my shoulders, I lost that match,” she told reporters.
It is what it is. It’s not about the tournament, I can’t play like that. I literally can’t do that again, that’s unprofessional. It’s not cool.
“I’m definitely going to be training tomorrow to make sure I don’t do this again.”

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Where does Serena go from here?

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“Sometimes you have a good record against somebody, you weren’t tested the last time, and you go in with thoughts that aren’t in the present. It’s just hoping to do what you did the last time and thinking about the next round.
“She’s getting older. The game is getting faster every year. Players are getting stronger. They’ve always been very fit.

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I think there’s a little anxiety from Serena that she has to finish the point before she gets on the back foot and defends too much.
“She did well hanging in with some rallies where she wasn’t playing well. Again, her opponent very quick around the court.
“Where does she go from here? Try and work on your movement for sure. Work on consistency. She needs more free points on the first serve.”

Then and now: US Open vs Aus Open

Williams was as clinical at the US Open as she was wasteful at the Australian Open, though Wang’s turnaround should also be celebrated.
But first, Williams. From converting five out of five break points at the US Open, she was just one from seven in Melbourne.

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From 25 winners and 10 unforced errors at Flushing Meadows, a staggering 56 errors (to 43 winners) flew from the Williams racket on Friday.
Her first-serve % was down (60 to 56), her win % on first (90 to 70) and second (64 to 50) serves was down.
Wang, meanwhile, did not hit a single winner in their US Open meeting. At the Australian Open, she hit 25.
And having failed to bring up a single break point four months ago, Wang converted three from a staggering 12 opportunities.

Service issues

Wilander added: “The older you get the better you serve usually. I can’t quite put my finger on if it’s only Serena’s serve that’s slightly off, or if it’s that everybody returns so much better that she’s trying to do too much.”
“She’s prolonging her career by not playing too much. Practicing serves on a court where no one is watching, with no opponent, is much easier than suddenly being in a match situation.
“You need to play matches. It’s about reacting. I feel when your serve is less good, you worry more about where it will land. When you serve well, you’re just going through the motion and know it will curve in.

‘Practice more, play more matches’

“The only way back is to practice more, obviously look after your body at her age, but play more matches and put yourself in that situation where you’re serving 15-30 down and there are nerves.
“It would be great practice for her to play more smaller tournaments. For some players it doesn’t really matter, but I believe she can focus as she hates to lose in any tournament again anyone.”
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