Nam lost to Harri Heliovaara of Finland 6(5)-7(7), 2-6 after one hour and 20 minutes.
The Tay Ninh native is now world No 498, while Heliovaara is world No 704. However, 28-year-old Heliovaara ranked 194th in 2011 and won three titles in a row last year including the Tunisia F27, the Estonia F2 and the Estonia F3.
By reaching the semi-final, Nam, 20, will win six points in the ATP rankings.
VNA/VNP
