Fognini will face Spaniard Guillermo Garcia-Lopez, a 7-6 (3), 4-6, 6-4 winner over eighth-seeded Federico Delbonis of Argentina.
Third-seeded defending champion Pablo Cuevas of Uruguay and fifth-seeded Leonardo Mayer of Argentina set up another quarterfinal in the clay-court event. Cuevas beat Austria's Sebastian Ofner 6-4, 7-6 (4), and Mayer topped Argentine countryman Carlos Berlocq 7-5, 6-4.