After a rest day that followed the conclusion of the group stages in the Costa Rican capital, Horn won his opening medal round matches against Ireland's Mark Murphy, who he beat 15-3, 15-1, and Edwin Galicia of Guatemala, who he defeated 15-14, 15-3.

The US player thus earned a last eight meeting with Colombia's Mario Mercado.

He had in turn beaten Venezuela's Luis Felipe Zea 15-1, 15-4 and Canada's Coby Iwaasa 15-13, 10-15, 15-3.

On the other side of the draw, Mexico's second seed Daniel De La Rosa also reached the last eight, where he will meet Colombia's Sebastian Franco.

The other quarter-finals will see third seed Charlie Pratt of the US play Canada's Samuel Murray and Conrado Moscoso of Bolivia meet Mexico's fourth seed Rodrigo Montoya.

After receiving a bye, Mexico's Longoria won her round-of-16 match against Jenny Daza of Bolivia 15-2, 15-11 and now faces Colombia's Adriana Riveros.

Should she win that, her semi-final will be against the winner of the match between Yasmine Sabja of Bolivia and Argentina's former world number two Maria Jose Vargas.

US second seed Rhonda Rajsich, who also earned a bye, won her match against Japan's Harumi Kajino 15-7, 15-5 to face Natalia Mendez of Argentina in her quarter-final.

The winner will play either third seed Samantha Salas of Mexico or Argentina's Ana Gabriela Martinez.