text: Reigning champion Novak Djokovic dug deep to avoid a shock exit at the hands of Alexandr Dolgopolov before powering into the quarter-finals of the Miami Open. The unseeded Dolgopolov - ranked 65th in the world, 64 places behind Djokovic - surprised the Serbian by winning a first-set tie-break and building a quick 4-2 lead in the second set. But Djokovic steeled himself and rallied to force a decider, which he wrapped up without much resistance from his deflated Ukrainian opponent. Novak Djokovic celebrates after securing a quarter-final place at the Miami Open . Novak Djokovic came back from a set down to reach the quarter-finals of the Miami Open on Tuesday . Alexandr Dolgopolov had both of his soles bandaged and won only three points in the final set . Djokovic claimed a succession of long exchanges in the second set to even the match and go on to win . The 6-7 (3/7) 7-5 6-0 triumph pits the world number one against David Ferrer in the last eight after the Spaniard saw off Gilles Simon 7-6 (7/5) 6-0 in a little over an hour and a half. Also through to the quarters are British number one Andy Murray and fourth seed Kei Nishikori. The Scot racked up a 500th career win by edging out Kevin Anderson 6-4 3-6 6-3 to book a meeting with Austrian Dominic Thiem, a 7-6 (7/5) 4-6 7-5 victor against Adrian Mannarino. Nishikori of Japan made light work of David Goffin and his 6-1 6-2 sees him progress to a match-up against big-serving American John Isner, who rallied to upset fifth seed Milos Raonic 6-7 (3/7) 7-6 (8/6) 7-6 (7/5) in a match which last two and three-quarter hours. David Ferrer celebrates after defeating Gilles Simon to book his place in the last eight . Simon is grounded after a fall during his defeat to Ferrer, who faces Novak Djokovic next . Andy Murray was given a celebratory cake to mark 500 wins on the ATP circuit after beating Kevin Anderson . Tomas Berdych also made it through to the quarter-finals by beating Gael Monfils . Kei Nishikori is also through to the last eight, defeating Serbia's Viktor Troicki . Czech challenger Tomas Berdych reached his sixth quarter-final of the season by beating Gael Monfils 6-3 3-2. The Frenchman conceded the match by retirement after suffering a heavy fall on court, and Berdych will meet Juan Monaco following the unseeded Argentinian's 6-3 6-3 conquest of Fernando Verdasco. In the women's competition, Carla Suarez Navarro lost the first set 6-0 but hit back to see off Venus Williams 0-6 6-1 7-5 and reach the semi-finals. There she will face Germany's Andrea Petkovic after the ninth seed beat Karolina Pliskova of the Czech Republic 6-4 6-2.
target: Novak Djokovic came from a set down to beat Alexandr Dolgopolov .
  The world No 1 remains in contention for his fifth Miami Open win .
  Dolgopolov became less mobile after receiving treatment to his feet .
  Djokovic faces David Ferrer next after Spaniard beat Gilles Simon .
  Andy Murray through after beating South Africa's Kevin Anderson .