Victor Estrella Burgos gets dramatic win vs. Ivo Karlovic in Quito

Victor Estrella Burgos' Quito magic continued in the most dramatic fashion Thursday.

Burgos, the two-time defending champion of the Ecuador Open, who is ranked 156 in the world, rallied to upset top-seeded Ivo Karlovic of Croatia 6-7 (7), 7-6 (5), 7-6 (8) in the second round at Quito.

The victory was the 12th in a row for Burgos, of the Dominican Republic, on the Ecuadorian clay courts.

Burgos survived 39 aces from Karlovic, the world's 18th-ranked player, and hit just three himself. Neither player faced a break point in the match, each winning at least 80 percent of his service points.

Next up for Burgos is a quarterfinal matchup with Italian qualifier Federico Gaio, who is ranked 179th. Gaio also went to a third-set tiebreaker Thursday, edging Austria's Gerald Melzer 6-7 (4), 6-3, 7-6 (2).

American Rajeev Ram also moved into the quarterfinals, knocking off Argentina's Nicolas Kicker 7-6 (5), 6-3. Rams, ranked 137th, will oppose third-seeded Paolo Lorenzi on Friday. Lorenzi, from Italy, beat Australia's Matthew Ebden 6-4, 6-4.

In the other quarterfinals, third-seeded Thomaz Bellucci of Brazil meets eighth-seeded Renzo Olivo of Australia, and qualifier Roberto Carballes Baena will take on second-seeded Albert Ramos-Vinolas in a battle of Spaniards.