Fifth-seed Joao Sousa has been eliminated from the Rio Open, adding to the list of favourites knocked out of the clay-court tournament in the early stages.
Norwegian Casper Ruud topped Portugal's Sousa 6-3 3-6 6-4 in the round of 16.
Top seeds Dominic Thiem of Austria, Italians Fabio Fognini and Marco Cecchinato and Diego Schwartzman of Argentina have already been ousted.
In the quarterfinals, Ruud will face Serbia's Laslo Dere, who eliminated Japan's Taro Daniel 6-4 6-2.
2016 Rio Open champion Pablo Cuevas of Uruguay advanced after beating Argentina's Juan Ignacio Londero 6-1 6-4.
Cuevas will face Spain's Albert Ramos-Vinolas in the quarter-finals.
Ramos-Vinolas defeated Argentina's Federico Delbonis 3-6 7-5 6-3.
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