Ash Barty’s reign as Adelaide International champion ended with a straight-sets defeat by American Danielle Collins on Wednesday.
The world No.1 led in both sets but ultimately succumbed to the relentless, powerful hitting from her opponent.
“It’s not always going to go your way,” said Barty.
“You can’t win every single tennis match, but you can sure as hell approach it the right way. And I think for my team and for me we did that this week, and we just didn’t quite get that result that went our way.”
Collins, who lost to Barty in last year’s semifinals, returns to the last four where she will take on Polish fifth seed Iga Swiatek or Aussie Maddison Inglis.
Barty had looked impressive in the early stages as she moved into a 3-1 lead, but she then lost rhythm on her serve and the aggressive returns of Collins began to dominate.
The American powered through five straight games to seal the set in 31 minutes.
An early break in second saw Barty take a 4-1 lead, only for Collins to storm back once again, breaking serve twice to set up a chance to serve it out.
A thumping cross-court forehand took Collins to match point and she completed a superb performance with an ace.
“I feel really comfortable playing here,” said Collins. “This is one of my favourite events and I always have such a fun time.
“I didn’t have the crowd on my side today but I still loved playing in front of so many fans. It just makes it such a fun atmosphere.”
Barty added: “(It’s) just disappointing, I think, to have two sets in a row where I went on a run of losing games.
“But also in that second set I felt like I probably went away from what was working a little bit on serve and just gave her an opportunity to get back into the match.”
In earlier results, second seed Belinda Bencic kicked off her campaign on a strong note with a straight-sets dismissal of Misaki Doi.
Bencic vaulted to a 6-1 5-1 lead against the Japanese left-hander before sealing a 6-1 6-3 win, a result moving her through to the quarterfinals.
There she joined Anastasija Sevastova, who earlier on Wednesday beat lucky loser Christina McHale in straight sets.
Coco Gauff beat world No.21 Petra Martic in three sets to set up a quarterfinal showdown against fellow American Shelby Rogers, while Australian qualifier Storm Sanders continued her dream run, beating seventh seed Yulia Puntintseva 6-4 5-7 6-1 for her biggest ever career victory.
Sevastova had originally been scheduled to meet in-form fourth seed Elise Mertens, only for the Belgian to pull out of the event shortly before the match, citing a shoulder injury.
“Unfortunately I felt something in my right shoulder during practice yesterday and I didn’t want to risk it,” explained Mertens, who had won 30 of her past 38 matches and had already won a WTA title in 2021.
“I hope I can come back to Adelaide next year.”
Instead, Sevastova lined up against the 85th-ranked McHale and stormed to a 6-4 6-1 victory, marking the first time she has won back-to-back matches since the US Open in 2019.
“It was a tough year for everyone I think last year. Also beginning of this year, maybe I wasn’t that confident but somehow I found my game, the last tournament in Australia, and I’m happy about it,” said the former world No.11.
“And now I’m playing in the quarterfinals, and yeah, I have nothing to lose.”
Sevastova will next face Jil Teichmann, after the Swiss beat No.8 seed Wang Qiang 3-6 6-3 6-3.
Teichmann’s countrywoman Bencic progressed in more dominant fashion, smacking 27 winners to Doi’s 11 to wrap up her victory at the Memorial Drive Centre Court in just 74 minutes.
Bencic, a former world No.4 now ranked 12th, dominated almost all of the match against Doi, who was broken in each of her first seven service games.
Trailing 5-1 in the second set, Doi finally held for the first time for 2-5, broke Bencic to close the gap to 3-5, and held two game points in the following game .
Bencic, however, wrenched back control and converted her third match point to progress.
“I felt really good on the court. It’s only my second time in Adelaide but I love this tournament, I feel very comfortable here and it was nice to play in front of the crowd. I’m really happy I won,” Bencic said.
“I feel really good in this place, it has a nice energy for me. I like the court, I like that it’s covered, and I’m just really happy to be in another quarterfinal, and hopefully I can win this time.”
This is the first time Bencic has advanced to the quarterfinals at an event since almost exactly a year ago, in Doha. She is bidding to appear in a semifinal for the first time since the WTA Finals in late 2019.
She will next face Sanders.