By Steve Gorten

KEY BISCAYNE – The world’s No. 1 player danced with disaster for much of two sets Tuesday, and then swept Alexandr Dolgopolov off the court with a finish as stunning as the deficit he had faced.

Down a set and 4-1 on stadium court, Djokovic won 12 of the final 13 games of the match to defeat the unseeded Dolgopolov 6-7 (3), 7-5, 6-0 and advance to the quarterfinals of the 2015 Miami Open.

“I just felt it wasn’t my kind of day,” Djokovic said. “The entire day was one of those days where you don’t feel so great mentally. But I fought. I fought my way through.”

“I was frustrated,” he added. “I was losing my composure in the first set because I didn’t feel good. So I was just trying to find a way to come back in the match.”

For a set and a half, Djokovic said, Dolgopolov was simply better than him. The 26-year-old Ukrainian, ranked No. 65 in the world, kept Djokovic out of rhythm with his unorthodox style. Djokovic was admittedly “tight” and “fighting a different battle – inside of myself. That was the biggest battle that I fought today.”

Djokovic, who has won the men’s title at the Miami Open three of the past four years and four times overall, also surrendered a set to his two previous opponents – Steve Darcis and Martin Klizan – in this year’s tournament.

He came to Crandon Park Tennis Center with a 19-2 record so far in 2015, but it hasn’t come without a price.

“It’s taking a little bit of a toll mentally on me,” he said. “I mean, I don’t feel that I’m very fresh on the court, even though I’m trying. This day off [Wednesday] will definitely serve me and help me recover mentally, mostly, because physically I’m fine. I feel OK. Hopefully, I can perform better in the next [match].”

Next week will mark Djokovic’s 141st consecutive week as the world’s No. 1 player, tying Rafael Nadal for the sixth longest stretch of all-time. Djokovic said it’s a streak he’s aware and proud of.

“It always gets me back into childhood and those early days of my tennis career and dreaming of becoming No. 1 in the world,” he said. “So I don’t take anything for granted. I believe that it took me a lot of hard work to get to where I am. Even more work to stay.”

Djokovic will next face sixth-seeded Spaniard David Ferrer, who advanced to the quarterfinals with a 7-6 (5), 6-0 win against No. 12 seed Gilles Simon of France. Ferrer has yet to lose a set at the Miami Open this year.

Fourth-seeded Kei Nishikori also advanced Tuesday, beating David Goffin of Belgium 6-1, 6-2. Andy Murray won his 500th career match, 6-4, 3-6, 6-3, against Kevin Anderson. Murray will face unseeded Austrian Dominic Thiem, who downed No. 28 seed Adrian Mannarino 7-6 (5), 4-6, 7-5.

Eighth-seeded Tomas Berdych of the Czech Republic and unseeded Juan Monaco of Argentina will face off in another quarterfinal.