Top men's seed Rafael Nadal booked his spot in the quarter-finals of the 2020 Australian Open after beating Nick Kyrgios in a thrilling contest on the Rod Laver Arena on Monday.
Simona Halep also claimed a last-eight spot with a comprehensive 6-4, 6-4 victory over No. 16 seed Elise Mertens on Monday.
No. 9 women's seed Kiki Bertens was knocked out by two-time Grand Slam winner Garbine Muguruza.
In the men's draw, 2014 champion Stan Wawrinka beat Russia's Daniil Medvedev in five sets, and Dominic Thiem knocked out Gael Monfils.
Australian Open - Saturday Results
(1) Rafael Nadal bt. (23) Nick Kyrgios: 6-3, 3-6, 7-6 (6), 7-6 (4)
(7) Alexander Zverev bt. (17) Andrey Rublev: 6-4, 6-4, 6-4
(5) Dominic Thiem bt. (10) Gael Monfils: 6-2, 6-4, 6-4
(15) Stan Wawrinka bt. (4) Daniil Medvedev: 6-2, 2-6, 4-6, 7-6 (2), 6-2
(4) Simona Halep bt. (16) Elise Mertens: 6-4, 6-4
Garbine Muguruza bt. (9) Kiki Bertens: 6-3, 6-3
(28) Anett Kontaveit bt. Iga Swiatek: 6-7 (4), 7-5, 7-5
(30) Anastasia Pavlyuchenkova bt. (17) Angelique Kerber: 6-7 (5), 7-6 (4), 6-2
Nadal had not dropped a set so far this year in Melbourne before Monday.
In Kyrgios, though, he faced a genuine challenger who had beaten him in three of their previous seven meetings.
The opening two sets were nip and tuck as the pair went blow-for-blow in a high-quality encounter:
Their last-16 clash hinged on the tiebreaks in sets three and four, which Nadal edged to come through in three hours, 38 minutes:
Former world No. 1 Halep reached the final at Melbourne Park in 2018, where she lost to Caroline Wozniacki.
After reaching the last eight for a fourth time on Monday, she is among the favourites to go one better this year by winning her third Grand Slam.
As No. 4 seed, she is the second highest ranked woman left in the tournament, and she is in the other half of the draw to top seed Ashleigh Barty.
Halep, 28, had to work hard to get past Mertens. The Belgian dragged herself back to parity after being a break down in the first set and two breaks down in the second.
But Halep showed impressive resolve to wrestle back the momentum on both occasions and prevail without going to a tiebreak:
The Romanian will meet Anett Kontaveit in the last eight after the No. 28 seed made history with her three-set win over Iga Swiatek:
Wawrinka stopped 23-year-old Medvedev is his tracks with a huge performance on the Margaret Court Arena.
The Swiss star, a veteran of six previous last-16 clashes at the Australian Open, looked to have lost the momentum when he trailed 2-1 after wining the first set.
But some devastating hitting saw him win in five sets after nearly three-and-a-half hours:
The 34-year-old finished the match with 71 winners in total compared to Medvedev's 44.
Wawrinka will play either Alexander Zverev in the quarter-finals.