Top seed Elina Svitolina continued to coast at the Claro Open Colsanitas, while eighth seed Irina Falconi was tested.
Svitolina thrashed Danka Kovinic 6-3 6-1 at the WTA International clay-court event in Bogota, advancing in just 57 minutes.
The Ukrainian was the beneficiary of nine Kovinic double-faults, the Montenegrin youngster suffering after a run to the quarter-finals as a qualifier at the Family Circle Cup in Charleston earlier in April.
Given the altitude in Bogota, Svitolina - a two-time WTA Tour winner - said she was keeping things simple.
"There's no real strategy for each opponent, but I'm just trying to play as many balls over the net as I can," Svitolina said.
"I've been trying to move really well around the ball to give myself space, which is key for my game anyway, and it gives me time here to set up properly for every shot. Also, I've tried to just accept this altitude is tough to play in, and not let it get me down during a match.
"I've been practising here for a while now and I'm feeling pretty confident so far."
Svitolina will meet Falconi in the last eight, after the American came from behind to down Dinah Pfizenmaier 5-7 6-2 6-3 in two hours, three minutes.
The winner of Svitolina-Falconi will take on an unseeded player in the semi-finals, with Teliana Pereira and Lourdes Dominguez Lino into the last eight.
Brazil's Pereira was a 7-5 7-5 victor over Mandy Minella, while Dominguez Lino saved two set points in a 7-6 (7-5) 6-0 victory over Brazilian qualifier Beatriz Haddad Maia.