MIAMI (Reuters) - Defending champion Novak Djokovic survived a scare from Alexandr Dolgopolov on Tuesday to reach the Miami Open 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.
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.
The gangly 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.
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.
Eighth-seed Berdych was leading 6-3 3-2 when Monfils retired after falling badly in the fifth game.
Berdych will next face Argentine Juan Monaco, a 6-3 6-3 winner over Spaniard Fernando Verdasco, who was coming off a win over compatriot and second seed Rafa Nadal.
Austrian Dominic Thiem reached his first Masters 1000 series quarter-final after beating France's Adrian Mannarino 7-6 (5) 4-6 7-5.
Editing by Frank Pingue