MELBOURNE, Australia — Anyone unfamiliar with Danielle Collins — and that could be forgiven, really, considering her 0-5 mark at majors until this Australian Open — got a sense of what she's all about during her surprisingly easy upset of former No. 1 Angelique Kerber.

Not just the 6-0, 6-2 scoreline Sunday that eliminated a three-time Grand Slam champion and put the unseeded Collins in the quarterfinals.

And not just the take-balls-early aggressive approach that produced a "Did I read that right?!" edge of 29-6 in total winners for Collins, a 25-year-old American who won a pair of NCAA singles titles at the University of Virginia.

But, instead, let's focus on this little detail: On the second set's second point, Kerber hit a forehand winner that she punctuated with a relatively innocuous "Come on!" that caught Collins' attention. So after claiming the following point with a drop shot, Collins stared down Kerber, leaned forward, shook a fist and screamed those same two words — except with a lot more oomph, stretching out the second syllable as if it were spelled with about a dozen O's.

"I'm my own person. I'm feisty. I love making it kind of a war. If somebody wants to get in my face on my unforced errors, I have no problem getting right back at them and making it a feisty match," said Collins, who knocked off No. 14 seed Julia Goerges in the first round and No. 19 Caroline Garcia in the third before taking care of No. 2 Kerber in the fourth.

"I love that. Embrace it," Collins continued with a laugh. "I love when things get competitive."

Her coach, Mat Cloer, confirmed that attitude extends to practice sessions, saying he'll hear from Collins during drills: "You missed before me."

Referring to Sunday's victory, Cloer said: "She was a little fiery at Angie, but I think that allowed her to say: 'You know what? I'm still here and I'm going to fight this through.'"

Next up for the 35th-ranked Collins on Tuesday will be Anastasia Pavlyuchenkova, who reached her fifth Grand Slam quarterfinal by coming back to beat 2017 U.S. Open champion Sloane Stephens 6-7 (3), 6-3, 6-3 in a match that ended at nearly 2 a.m.

The other quarterfinal on that side of the draw will be two-time Wimbledon champion Petra Kvitova against No. 15 Ash Barty, the first Australian woman to get this far at her country's Slam since Jelena Dokic a decade ago.

Barty took advantage of Maria Sharapova's 10 double-faults to beat the five-time major champion 4-6, 6-1, 6-4, while Kvitova eliminated 17-year-old Amanda Anisimova of the U.S. 6-2, 6-1.

Nothing was quite as impressive as the way Collins made Kerber look rather ordinary.

"Not too much to say," said Kerber, who defeated Serena Williams in the 2016 Australian Open final. "I mean, it was completely not my day."

Collins had a lot to do with that, to be sure.

She is supremely self-confident away from a tennis court — and on one, too, especially lately.

"From the very first point, I showed her that I wasn't going to let her into the match, that I was going to dictate the entire way through," said Collins, who had lost her only previous match against Kerber 6-1, 6-1, but that was on grass, not the sort of hard court used at Melbourne Park. "I stuck to my game plan. It clearly worked out well for me. Pretty much smooth sailing throughout the entire thing."

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