Second seed Johanna Larsson was sent tumbling out of the Rio Open on Thursday as world number 285 Paula Cristina Goncalves moved into the quarter-finals.
Larsson was the highest seeded player left in the draw after Teliana Pereira's first-round exit but she soon followed the top seed out as Goncalves recorded a 6-4 6-4 triumph - the biggest win of her career.
Despite losing her serve early in the first set, Goncalves battled back and from 4-2 down won four in a row to move ahead in the match.
The second set was a much scrappier affair and it was the Brazilian who came out on top, breaking Larsson for the third time in the set to seal the match.
Third seed Danka Kovinic had no such problems, though, as she cruised past Silvia Soler-Espinose 6-2 6-3, while Lara Arruabarrena - the sixth seed - needed three sets to see off Ana Bogdan 7-5 5-7 6-3.
Meanwhile, Petra Martic is also through as she raced through the deciding set against Marina Erakovic to win 7-6 (7-2) 5-7 6-2 and set up a last eight match with Arrurabarrena.