Williams falls in seed scattering at Miami Open
The world number one lost for the first time since 2012 in Miami, beaten by Svetlana Kuznetsova. Muguruza, Radwanska and Murray also went out.
Serena Williams' bid for a ninth Miami Open title came to a shock end when the world number one was beaten 6-7(3) 6-1 6-2 in the fourth round by 15th-seeded Russian Svetlana Kuznetsova on Monday.
The loss on the Miami hard courts was the first since 2012 for Williams, who had swept the last three titles in her unofficial home tournament.
"I'm really thrilled," said Kuznetsova after registering her first win over Williams since 2009. "I'm sorry fans, who are disappointed that Serena's not going to keep playing, but for sure she'll be at more events than here. I'm really happy with my performance. I tried to stay at a good level the whole game. I think I did that pretty well and I'm happy with the way I served today."
It was a day of dramatic upsets at Crandon Park, as Williams stepped onto the Stadium court for her Round of 16 match immediately after third-seeded world number two Agnieszka Radwanska of Poland was tripped up by 19th-seeded Swiss Timea Bacsinszky 2-6 6-4 6-2.
Radwanska was the winner on the Miami hardcourts in 2012 before Serena Williams embarked on her three-title run.
The upsets continued into the afternoon with fourth-seeded Spaniard Garbiñe Muguruza falling 7-6(6) 7-6(4) to 13th-seeded Belarusian Victoria Azarenka, still in top form following her victory this month at Indian Wells.
Second-seeded Angelique Kerber narrowly avoided being another victim as she survived Timea Babos 6-2 3-6 6-4 in the day's late match.
A tight first set saw both Williams and Kuznetsova register a break but neither player could gain the upper hand, sending the opener to a tie-break which the top-seeded American dominated 7-3 with the help of a pair of thundering aces.
A battling Kuznetsova controlled the second set from the start, breaking the 21-times grand slam winner to go up 3-1 then sweeping the next three games to level the contest at a set apiece.
The Russian upped the pressure with a pair of breaks to start the third as she stormed through the opening three games before Williams finally stopped the bleeding with a break of her own at 3-1.
The relief was brief, however, as former U.S. and French Open champion Kuznetsova immediately hit back with yet another break and went on to finish off the upset in just over two hours.
In other action, fifth-seeded Romanian Simona Halep eased into the quarters with a tidy 6-3 6-4 win over British wildcard Heather Watson. Britain, however, will be represented in the last eight as Johanna Konta tamed another Romanian, Monica Niculescu, 6-2 6-2.
Only two of the top 12 seeds -- number two Angelique Kerber and number five Simona Halep -- remain on the women's side.
Top-ranked Novak Djokovic is the last top-five man remaining after world number two Andy Murray crashed out on Monday to Bulgarian 26th seed Grigor Dimitrov 6-7 (1/7), 6-4, 6-3. Only three of the men's top eight made the last 16 at this year’s tournament.
Two-time Grand Slam champion Murray failed in his bid for a third Miami trophy and fourth final in five seasons. The 28-year-old Scotsman dominated the tie-breaker but fell behind 4-0 in the second set and stumbled after leading 3-1 in the third, swatting a forehand long on match point to fall after two hours and 24 minutes.
"It's the best result of the year for me," Dimitrov said. "I just played better in the good moments. That was it."
Japanese sixth seed Kei Nishikori cruised into the fourth round by routing Ukraine's 27th-seeded Alexandr Dolgopolov 6-2, 6-2.
"I played a very solid match," Nishikori said. "It's not easy when you're in the top 10 and everybody is playing their best against you."
Nishikori, the top-ranked player remaining in his half of the draw, plays Tuesday for a quarter-final berth against Spanish 17th seed Roberto Bautista Agut.