Serena Williams blasted past Simona Halep to set up an Australian Open semi-final showdown with Naomi Osaka on Tuesday, as Russian qualifier Aslan Karatsev extended his fairytale run.
Williams took a step towards a record-equalling 24th Grand Slam title with a 6-3, 6-3 dismantling of second seed Halep, the American's nemesis in the 2019 Wimbledon final.
Williams, 39, said her level was improving ahead of her meeting with Japan's Osaka, who came out on top in their tempestuous 2018 US Open title match.
"Definitely think this is the best match I have played this tournament, for sure," said the 10th seed.
"Obviously I had to, going up against the number two in the world, so I knew I had to do better."
Their semi-final promises much after Osaka, the reigning US Open champion, looked in great touch in her 6-2, 6-2 win over Taiwan's Hsieh Su-wei.
Displaying great focus against the awkward Hsieh, ranked 71 and playing her first Slam quarter-final aged 35, Osaka hit 24 winners and was detained on Rod Laver Arena for only 66 minutes.
"I told myself just to be really intense from the beginning," said the Japanese star, the reigning US Open champion.
"I felt like I knew what to expect and that I couldn't afford to be lazy with my footwork or anything."
Elsewhere, 114th-ranked Karatsev became the first man to reach a Grand Slam semi on debut when he ousted a hobbling Grigor Dimitrov 2-6, 6-4, 6-1, 6-2.
The 27-year-old has knocked out three seeds on his run to the last four, where he will face world number one Novak Djokovic or US Open finalist Alexander Zverev.
"It's an unbelievable feeling," said Karatsev, whose career so far has been badly compromised by injury.
"It was tough at the beginning for me to hold my nerves, but I tried to find a way to play."