Britain's Johanna Konta crashed out of the Miami Open after a 6-1 6-2 defeat to ninth seed Petra Kvitova, while Viktoria Azarenka set up a showdown with Ashleigh Barty.
Konta had picked up just her second win of the season when she beat Magda Linette in the second round earlier in the week but on Saturday night she was no match for Kvitova who converted 80 per cent of her break points.
The Czech, twice a Wimbledon champion, won her first title in almost two years earlier this month when she beat Garbine Muguruza to win the Qatar Open and she needed just 58 minutes to see off Konta and set up a last-16 meeting with fifth seed Elina Svitolina.
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Elsewhere three-time Miami champion Azarenka set up a fourth-round clash against world No 1 Barty after she beat Angelique Kerber in a clash of Grand Slam champions.
Azarenka rallied from a 4-1 deficit in the first set to seal victory and won six of the last seven games to take the match as she overpowered Kerber 7-5 6-2 to seal her showdown with Barty - the top seed who will pose a very different threat.
"She's a very talented player. I always have been a huge fan of her game and the way she plays, the way she handles herself," said Azarenka after her victory.
"She has a lot of variety. She has pretty much every single shot there is. [It's] going to be a great match."
Barty won 6-3 6-2 against Jelena Ostapenko. The defending champion had toiled for nearly two-and-a-half hours against qualifier Kristina Kucova in her opening match, needing to save a match point, but was much more solid against Ostapenko.
Barty reeled off the last six games in the second set to seal victory. Also through is wildcard Ana Konjuh who beat No 15 seed Iga Swiatek 6-4 2-6 6-2 in two hours and 14 minutes. She will face Anastasija Sevastova, who advanced to the fourth round after Simona Halep withdrew due to a shoulder injury.
Elina Svitolina overcame No 30 seed Ekaterina Alexandrova 7-6 (1) 6-4, Aryna Sabalenka beat Veronika Kudermetova in another tight two-setter and will go on to face Marketa Vondrousova who knocked out 11th seed Belinda Bencic 4-6 6-4 6-4.
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In the men's event, Stefanos Tsitsipas overcame Damir Dzumhur 6-1 6-4 to set up a date with Kei Nishikori who continued his return to action with victory over Aljaz Bedene.
World No 5 Tsitsipas served confidently and hit winning shots off both sides to progress to the third round after 68 minutes, but Nishikori had a tougher assignment needing two hours and 50 minutes to beat Bedene 7-6 (6) 5-7 6-4.
It was Nishikori's second win in as many weeks against Bedene, having also beat the Slovenian 6-4 6-4 at last week's Dubai Duty Free Tennis Championships.
With Alexander Zverev the highest-profile exit so far, a number of big names made it through. Milos Raonic cruised into the third round overpowering Jordan Thompson 6-2 6-1 and will now face Ugo Humbert after he defeated Joao Sousa 6-1 6-4.
Diego Schwartzman made light work of Yasutaka Uchiyama, Andrey Rublev lost just three games against Tennys Sandgren, Denis Shapovalov needed three sets to beat Ilya Ivashka and the in-form Aslan Karatsev was also a straight-sets winner as he advanced 6-4 6-3 against Mikhail Kukushkin.
Marin Cilic needed three sets to overcome 13th seed Cristian Garin, who joined Fabio Fognini and Alex de Minaur in crashing out at the third round stage. Sebastian Korda came from a set down to beat 10th seed Fognini 1-6 6-4 6-2 while Colombia's Daniel Elahi Galan also came from behind to shock De Minaur 4-6 6-3 6-4.
And 19-year-old Lorenzo Musetti, competing at the Miami Open for the first time, defeated 23rd seed Benoit Paire 6-3 6-3.
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