Andy Murray and Serena Williams were the big losers in the Miami Open as they were dumped out in the third and fourth round respectively on a day of upsets in Florida.

World number two Murray cut a disconsolate figure as he was beaten 6-7 (7/1) 6-4 6-3 by the impressive Grigor Dimitrov, who enjoyed a first win against a top-10 opponent in 13 matches.

Dimitrov dominated from the baseline against Murray, who contributed to his downfall with more than 50 unforced errors.

In the women's event, world number one Williams sees her wait for a first title of the season go on as she surprisingly lost in three sets to 15th-seed Svetlana Kuznetsova.

Williams won the first set on a tie-break before going on to capitulate as the Russian stormed back to take the final two sets 6-1 6-3.

"It's obviously disappointing, but I've won here a lot, so it's okay," Williams said in her post-match press conference.

"I did the best that I could, so to the fans, I did the best that I could today, and I can't win every match. These players come out, and they play me like they've never played before in their lives. So, you know, it's the best that I could do today."

In the men's event Jo-Wilfried Tsonga was another victim of an upset as the ninth-seed was downed 2-6 6-3 7-6 (7/3) by Spaniard Roberto Bautista Agut.

There were no such problems for sixth seed Kei Nishikori, who is now the second highest seed left in the competition, after he easily disposed of Alexandr Dolgopolov 6-2 6-2.

Milos Raonic had to battle hard to get past American Jack Sock, winning 7-6 (7/3) 6-4, while Gael Monfils set up a fourth-round meeting with Dimitrov after easing past Pablo Cuevas 6-3 6-4.

Nick Kyrgios made safe passage to the next round with a 6-4 6-4 win over Tim Smyczek, Andrey Kuznetsov came from behind to beat Adrian Mannarino 2-6 7-5 6-0 while Damir Dzumhur edged his clash with Mikhail Kukushkin 4-6 6-1 6-2.

Victoria Azarenka is on course for back-to-back WTA titles as the Indian Wells champion needed two tie-breaks to beat fourth-seed Garbine Muguruza 7-6 (8/6) 7-6 (7/4).

That set up a meeting with British number one Johanna Konta, who became the first Brit to reach the quarter-finals of the Miami Open with a 6-2 6-2 success over Monica Niculescu.

Heather Watson missed out on that accolade as she was beaten 6-3 6-4 by Simona Halep, while Timea Bacsinszky shocked third-seed Agnieska Radwanska, coming from behind to win 2-6 6-4 6-2.

Madison Keys was too good for Irina-Camelia Begu in a 6-3 6-1 victory, Ekaterina Makarova dispatched Elina Svitolina 6-1 6-4 and Angelique Kerber beat Timea Babos 6-2 3-6 6-2 in a game that finished well past midnight.