Dominic Thiem, Alberto Ramos-Vinolas advance at Rio Open

Second-seeded Dominic Thiem of Austria and No. 5 Alberto Ramos-Vinolas advanced to the quarterfinals of the ATP Rio Open in Rio de Janeiro, Brazil, on Wednesday with straight-set victories.

Thiem ousted Dusan Lajovic of Serbia 6-2, 7-5 in a match without an ace recorded while Ramos-Vinolas knocked off Fabio Fognini of Italy 6-2, 6-3.

Thiem is the highest remaining seed after No. 1 Kei Nishikori of Japan was upset 6-4, 6-3 on Tuesday.

"The tournament is strong," Thiem said. "If you're not 100 percent you can lose to anybody. Everybody is very strong."

Also advancing to the quarterfinals were Nicolas Kicker of Argentina, who defeated fellow qualifier Arthur De Greef of Belgium 6-3, 6-3, and Diego Schwartzman, a 6-4, 7-6 (1) winner over Federico Delbonis in a battle of unseeded Argentinians.

Ramos-Vinolas used four aces while winning 61 percent of his first serve points and 63 percent on his second serve. He'll meet Kicker in the quarterfinals while Thiem takes on Schwartzman.