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Second seed Ana Ivanovic progressed at the Abierto Monterrey on Thursday, while main-draw debutant Julia Boserup continued her dream run.
Serbian Ivanovic cruised past Canadian qualifier Aleksandra Wozniak 6-4 6-2, taking just one hour and eight minutes to move into the quarter-finals at the WTA International event.
Ivanovic and Danish third seed Caroline Wozniacki are the red-hot favourites to win the title in Mexico, with the only other seed still in contention being Magdalena Rybarikova (six) and Monica Puig (eight).
American qualifier Boserup, though, is shaping as the feel-good story of the event, as she continued her first career Tour-level tournament with a 2-6 6-2 6-1 win over compatriot Allie Kiick.
Next up for the world number 302 will be Serbia's Jovana Jaksic - ranked 137th - with both players presented with a great chance at a semi-final berth.
Puerto Rico's Puig dispatched of American Nicole Gibbs 6-4 6-2, and will meet Japanese veteran Kimiko Date-Krumm in the last eight.
Slovakia's Rybarikova was on court for just 47 minutes before opponent Ayumi Morita of Japan retired injured, with the sixth seed winning 6-4.
Rybarikova will meet Ivanovic for a spot in the final four.