BOGOTÁ, Colombia - Gisela Dulko edged Rossana de los Ríos, 57 61 63, on Thursday to earn a place in the quarterfinals of the Copa Sony Ericsson Colsanitas. The third-seeded Argentinian converted on seven of 14 break point opportunities in the almost two-and-a-half-hour match.

Dulko, ranked 46th in the world, is seeking her fourth Sony Ericsson WTA Tour singles title and first since last May in Fès, to go along with seven in doubles. Her previous best result in Bogotá was also a quarterfinal appearance in 2006.

Dulko will play No.6 seed Mathilde Johansson on Friday. Johansson, who has yet to win a title, beat qualifier Katalin Marosi, 64 61. Masa Zec Peskiric versus Edina Gallovits is the other quarterfinal in the top half of the draw.

The bottom half of the draw experienced a significant upset Thursday, when No.2 seed Carla Suárez Navarro retired with a right elbow injury while trailing Betina Jozami just 16 minutes into the first set. She first suffered the injury during her singles victory on Tuesday, and subsequently withdrew from the doubles event.

Jozami has another seed to get through next in order to get a step closer to her first title: No.7 seed María José Martínez Sánchez, who cruised past Arantxa Parra Santonja, 64 63. It was Martínez Sánchez's fifth win in seven career matches against the fellow Spaniard. The winner of the Jozami-Martínez Sánchez match will take on the winner of Friday's quarterfinal between Patricia Mayr and Ioana Raluca Olaru.