John Isner erased the only break point he faced Tuesday and outlasted Canadian Milos Raonic in a serving duel at the Miami Open, 6-7 (3), 7-6 (6), 7-6 (5).

Isner, seeded 22nd, is the only American left in the men's draw. With the win, he advanced to the Key Biscayne quarterfinals for the first time.

Isner, who has yet to lose serve in three matches, was down two mini-breaks in the second-set tiebreaker before he rallied. He hit 22 aces to 12 for Raonic, with a top speed of 143 mph.

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The No. 5-seeded Raonic, from Thornhill, Ont. netted a backhand on the final shot of the match. Isner won 116 points, Raonic 115.

Defending champion Novak Djokovic survived a scare from Alexandr Dolgopolov to reach the quarter-finals while Andy Murray won the 500th match of his career to reach the last eight.

Djokovic was made to work for his 7-6(3) 7-5 6-0 win over world number 65 Dolgopolov.

After dropping the first set the top-seeded Serbian found himself in even deeper trouble by falling behind 4-1 in the second and facing the threat of an unexpected early exit.

But Djokovic dug deep to turn things around, breaking to get the set back on serve at 4-3 to the Ukrainian and then broke again for a 6-5 lead.

Having seen his chance of an upset slip through his hands, Dolgopolov faded quickly and badly dropped the third set where a dominant Djokovic won 24 of 27 points.

"I was literally a game or two from losing the match. I'm just happy to be able to bounce back," said Djokovic.

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"These particular matches do help me in a certain way mentally to gain that confidence and self belief in a way that I never give up and battle till the last point, and it sends a message to the other players, as well," he added.

Djokovic, who is seeking a fifth title at Key Biscayne, will face Spaniard David Ferrer in the quarters.

World number four Murray beat South African Kevin Anderson 6-4 3-6 6-3 to become the 46th man in the Open Era to reach 500 career wins and the first British male. He is one of only nine active players to have reached the milestone.

Anderson fought back well in the second but after trading early breaks in the third the Scot took control breaking his South African opponent again to grab a 3-1 advantage and never looked back.

Murray will face Austrian Dominic Thiem, who reached his first Masters 1000 series quarter-final after beating France's Adrian Mannarino 7-6(5) 4-6 7-5.

Czech Tomas Berdych made it six quarter-finals out of six tournaments this year after he advanced when Frenchman Gael Monfils retired in the second set after a bad fall. Berdych was leading 6-3 3-2.

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Berdych will next face Argentine Juan Monaco, a 6-3 6-3 winner over Spaniard Fernando Verdasco.

Japan's Kei Nishikori, the fourth seed, beat Belgian David Goffin 6-1 6-2 and will face Isner.

Spain's Carla Suarez Navarro came back from a dreadful first set to defeat three-times Miami Open champion Venus Williams 0-6 6-1 7-5 and set up a semi-final clash with Germany's ninth seed Andrea Petkovic.

Petkovic booked her place in the last four after a 6-4 6-2 win over 14th seeded Czech Karolina Pliskova.

Williams utterly dominated the first set, crushing the Spaniard 6-0 in less than half an hour but her opponent was able to regroup and battle back in impressive style.

Suddenly regaining her confidence Suarez Navarro won the first four games and went on to take the second set 6-1.

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The third set bucked the trend for one-sided exchanges until Suarez Navarro broke to go 5-4 up only for Venus to break back straight away.

The Spaniard won the last two games however to continue an impressive season that has seen her reach two other semi-finals and make the last eight at Indian Wells for the first time.

"It was a crazy match, crazy first two sets. Venus was unbelievable at the beginning. I started a bit nervous but even if you lose the first set you are still in the competition and I am happy with the way I came back," said Suarez Navarro.

Williams said she had struggled to find consistency.

"I just made a little too many errors and I was going for it the whole match. Towards the end just never found the happy medium between being aggressive and putting the ball in the court," she said.

Petkovic made a blistering start, going up 4-1 in the first set but the 23-year-old Pliskova powered her way back to 4-4 and then had three break points, all of which were saved.

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Petkovic, the 2011 Miami semi-finalist, won the next five games and wrapped up the match in one hour, 16 minutes.

"I was playing really well at the start but I couldn't see the ball on my serve with the sun on one side and I was struggling," said Petkovic.

"Karolina also started playing really well and I was a little lucky at the end of the first set. But then I got better and better from there," she said.

Wednesday's quarter-finals see top seed Serena Williams take on Germany's Sabine Lisicki while third-seed Romanian Simona Halep faces American Sloane Stephens.

Files from Reuters were used in this report