Result will see 11th seed Konta drop from 14th in world rankings to outside top 20
Venus Williams beats Johanna Konta at Miami Open on day of feisty exchanges in men's draw
Johanna Konta's defence of her Miami Open title ended on Monday as Venus Williams beat the British No 1 5-7, 6-1, 6-2 in their fourth-round match in Key Biscayne.
The result will see 11th seed Konta drop from 14th in the world rankings to outside the top 20.
Williams, making her 19th appearance at the tournament and reaching the quarter-finals for a 13th time, enjoyed the vocal home support as she produced an outstanding display after coming off second best in a wobbly opening set.
The 37-year-old player will face fellow American Danielle Collins in the last eight. Collins triumphed 3-6, 6-4, 6-2 against Puerto Rico's Monica Puig, who had seen off world No 2 Caroline Wozniacki at the weekend.
Spanish third seed Garbine Muguruza followed Konta out of the tournament, with Sloane Stephens winning 6-3, 6-4. Stephens - seeded 13 - will next play 10th seed Angelique Kerber, who rallied for a hard-fought 6-7, 7-6, 6-3 victory over China's Yafan Wang.
Two-time Wimbledon champion Petra Kvitova was sent packing in the late match, with French Open champion Jelena Ostapenko seeing off the rain as well as the ninth-seeded Czech. The Latvian fifth seed prevailed 7-6, 6-3 to reach the last eight, where she will take on Ukraine's Elina Svitolina.
Fourth seed Svitolina overcame Australian Ashleigh Barty 7-5, 6-4.
Fifth seed Karolina Pliskova was leading Zarina Diyas 6-2, 2-1 when the Kazakh retired injured. The Czech will next take on Victoria Azarenka, who overpowered fellow former Miami champion Agnieszka Radwanska 6-2, 6-2.
Canada's Denis Shapovalov ended the run of 11th seed Sam Querrey with victory in their third-round match.
Shapovalov, the world No 46, beat his American opponent, ranked 32 places above him, 6-4, 3-6, 7-5.
Querrey was made to pay for squandering nine of the 12 break points he carved out as Shapovalov took his chances when they came along.
The 18-year-old player will take on Borna Coric in Round 4, the 29th seed having upset American eighth seed Jack Sock 5-7, 7-6, 6-3 on Monday.
Fernando Verdasco had to fight back from a set down against Australian qualifier Thanasi Kokkinakis 3-6, 6-4, 7-6 to secure a fourth-round meeting with fellow Spaniard Pablo Carreno-Busta, the 16th seed who ousted American Steve Johnson 6-4, 6-4.
Verdasco and Kokkinakis were involved in a heated exchange during a third-set change of ends, which spiralled after the former questioned the conduct of his opponent's father in the crowd. A row ensued, after which the match continued and concluded with a frosty handshake.
The bad feeling continued on social media, with Nick Kyrgios tweeting that he hoped Kokkinakis beat "the saltiest dude" Verdasco. Kyrgios later deleted the tweet, with Verdasco then accusing the Australian of lacking the "courage" to stand by his words.
Kyrgios hit back with another tweet which he later deleted, in which he said: "I would honestly have told it to Fernando's face, the reason I deleted my previous tweet was because I didn't want to cause unwanted attention, but I'm just gonna leave this here. Thanks for blocking me, I'm sure that took a lot of courage x".
Back on the court, Kyrgios, seeded 17, swept aside Fabio Fognini 6-3, 6-3 and will next face fourth seed Alexander Zverev, who overcame a first-set blip en route to a 2-6, 6-2, 6-4 triumph over David Ferrer.
South Africa's Kevin Anderson also had his work cut out but battled back to beat Russia's Karen Khachanov 4-6, 6-2, 6-3. He will play either Frances Tiafoe or Tomas Berdych in Round 4.
Their match was finely poised, the American leading the 10th-seeded Czech 5-4 in the third set when play was suspended due to darkness.