Top seed and defending champion Juan Martin Del Potro marched into the quarter-finals of the Estoril Open in Portugal with a 6-1 6-0, 62-minute demolition of home hope Rui Machado.
The Argentinian former US Open champion broke his opponent five times in total to set up a last-eight clash with another former champion, Spaniard Albert Montanes, who beat American Bobby Reynolds 4-6 6-4 6-3.
Fourth seed Albert Ramos beat Germany's Bjorn Phau 7-5 6-0 and next up for the Spaniard is Brazilian wild card Joao Souza, who led fifth seed Denis Istomin 3-6 6-3 4-2 when the Uzbek retired hurt with a back problem.
In the women's quarter-finals, top seed Roberta Vinci advanced with a topsy-turvy 6-2 1-6 6-4 win over Russia's Nadia Petrova, and will play sixth seed Kaia Kanepi, who beat fourth seed Petra Cetkovska 6-3 3-6 6-3.
Italian qualifier Karin Knapp, ranked 133 in the world, continued her dream week with a 7-6 (7/4) 2-6 6-4 win over Kazakh Galina Voskoboeva. She will play Carla Suarez Navarro, who beat Spanish compatriot Silvia Soler-Espinosa 6-3 6-3.
