A ruthless Iga Swiatek destroyed German lucky loser Eva Lys with a 6-0 6-1 win on Monday to breeze into the quarter-finals of the year's opening Grand Slam for the second time, while American Madison Keys upset sixth seed Elena Rybakina 6-3 1-6 6-3.
Five-times Grand Slam champion Swiatek came into the match having lost only 10 games in the tournament and the Pole sent out another warning to her title rivals by dismantling Lys in 59 minutes on Rod Laver Arena.
"Great, that was my first night session and I'm glad I have the chance to play on Rod Laver Arena," Swiatek said.
"I enjoyed it, which is the most important thing...I'm still 23, so there's a lot to improve. I don't feel I'm at my peak. But these matches give me a lot of confidence.
"We don't know what's going to happen in the future, maybe I'll be better. I'm so glad I was able to play my game...I'm feeling really comfortable and we're going well."
One of several searing forehand winners helped 2022 semi-finalist Swiatek break Lys for the first time and the 23-year-old did not take her foot of the gas pedal as she closed out the first set in 24 minutes.
World number 128 Lys had enjoyed a historic run after she replaced Anna Kalinskaya in the main draw following a loss in the qualifying event but there was only more suffering in store for the Kyiv-born player.
Lys managed a smile and pumped her fist when she went 40-30 up after conceding the opening three games and soaked up the loud applause after getting on the board to ensure she would avoid the dreaded double bagel.
Swiatek broke for the fifth time after a six-deuce game and served out in style to book a last-eight meeting with Emma Navarro or Daria Kasatkina.
Adelaide Open champion Madison Keys had lost to Kazakhstan's Elena Rybakinba in their last two encounters but was well in control for most of the last 16 tie, barring a rough patch in the second set when she lost four straight games.
Rybakina seemed to be struggling with a lower back injury that had affected her in the third round and Keys was able to play aggressively to neutralise her big serve and take control of the rallies.
"Her serve is such a weapon, so I knew that if I could just try to make at least some of her service games a little bit competitive, then I had a chance," said the 19th seed, who chalked up her third win over a top-10 player this month.
"So I was basically just trying to make anything that I could get my racket on back over the net, which worked sometimes."
The decider was neck-and-neck early on at 3-3 before Keys moved up a gear and sealed her spot in the next round with a searing cross-court winner on her second match point.
She will next play Ukraine's Elina Svitolina, who beat Veronika Kudermetova 6-4 6-1 earlier on Monday.