Top-seeded Kei Nishikori is finding his footing on clay.
After struggling in his first match in the Argentina Open, the Japanese defeated No. 6 Joao Sousa of Portugal 6-1, 6-4 on Friday to reach the semifinals of the outdoor clay-court event.
Pablo Carreno Busta of Spain and Alexandr Dolgopolov of Ukraine also reached the last four.
Carreno Busta defeated fellow Spaniard Albert Ramos-Vinolas 6-3, 4-6, 6-4, and Dolgopolov won over Gerald Melzer of Austria 7-5, 6-4.
Carreno Busta will face Dolgopolov in one semifinal on Saturday, while Nishikori faces either Carlos Berlocq of Argentina or Thiago Monteiro of Brazil.