The dream run of Ukrainian qualifier Dayana Yastremska has led to a grand slam quarterfinal at Melbourne Park.

Elina Svitolina's hopes of victory ended after just three games, while a protester stopped play at Margaret Court Arena.

Here are five quick hits from day nine at Melbourne Park.

1. Yastremska marches onto maiden quarterfinal after defeating former champion Azarenka

Qualifier Dayana Yastremska has continued her fairytale run into the quarterfinals of the Australian Open on Monday with a 7-6(7/6), 6-4 upset of two-time champion and 18th seed Victoria Azarenka.

The Ukrainian world number 93, who stunned Wimbledon champion Marketa Vondrousova in the first round, had to fight hard but was rewarded for her aggression with 38 winners to forge on into a half of the draw devoid of top 10 seeds.

"I feel like my heart is going to jump out of my body," the 23-year-old said after the biggest win of her career.

"I was losing the tie break, I was losing the second set, I was always felt like I was running behind the train. But I think I'm a little bit of a fighter so that's why I won this match."

Azarenka had a first-set lead and served for the set but Yastremska kept up the pressure through five deuces and finally converted her fourth break point to force a tie breaker.

The tie breaker was just as tight but the Ukrainian sealed it with her 21st winner, a blistering forehand that was just too fast and too deep for Azarenka.

Belarusian Azarenka came out firing, racing to a 3-0 lead almost before Yastremska had time to catch her breath.

The Ukrainian stalled Azarenka's progress and then went back on the attack, finding her rasping winners again to win five straight games.

She held her nerve serving for the match two games later, lashing across one more big backhand to set up a meeting with Czech world number 50 Linda Noskova in her maiden grand slam quarterfinal.

2. Elina Svitolina suffers tearful exit

An 11-minute opening game had us dreaming of a classic fourth-round encounter between 19th seed Elina Svitolina and teenage sensation Linda Noskova.

But an injury to Svitolina's back in the closing stages of that marathon game would soon bring the match — and the Ukranian's tournament — to a premature halt.

Svitolina had extensive work done to her hip and back after the second game, trying to release whatever had tightened and was causing her problems.

But despite giving it one more go in a third game, Svitolina could go on no longer. Noskova was unsure how to react having reached her maiden grand slam quarterfinal, as Svitolina struggled to hold back the tears.

3. Medvedev gives a masterclass, winning fans with post-match interview

Daniil Medvedev's relationship with the audience has always been interesting.

The Russian seemingly plays his best tennis when he is in a combative mood, and sometimes battling the crowd is the best way for the former US Open winner to get into the fighting spirit.

He has previously had run-ins with crowds at grand slams, and once told the Melbourne Park crowd they were being disrespectful during a post-match interview. 

But Monday showed the other side of Medvedev's relationship with the crowd.

Following a four-set win over Portugal's Nuno Borges, Medvedev produced one of the best post-match discussions you are likely to watch

He charmed the crowd with his personality and humour, before giving an insight into how he prepares to return serve. 

Asked by former Australian Open champion turned broadcaster Jim Courier, Medvedev's explanation about the evolution of his game at the top level was a glimpse into what makes a great player.

4. Protester stops play

The fourth-round men's singles match between Alexander Zverev and Cameron Norrie had a brief pause following a protester throwing paper onto the court.

The demonstration came during the third set, with Norrie serving while 1-4 down at Margaret Court Arena.

Images show a woman throwing paper onto the court.

Those images show the words "Free Palestine" on the paper which was hurled onto the court.

Two patrons appeared to remove the protester, with the match being halted for a couple of minutes.

In a statement late on Monday evening, a Tennis Australia spokeswoman praised two patrons who stepped in to stop the protester.

"As soon as the behaviour was identified and reported, venue security was deployed to detain the individual," she said.