Nam, the No 6 seed, won 6-3, 7-6 (3). He will next face eighth-seeded Heliovaara Harri of Finland in the semi-finals.
The Tay Ninh native remains among the top 500 tennis players in the world, as of early 2018, according to the Association of Tennis Professionals (ATP) rankings.
However, compared to the rankings in late 2017, Nam has dropped one place to 498th in the men’s singles rankings.
