Nam, ranked 565 in the ATP, beat Sadio Doumbia of France, ranked 442, in the fourth qualifying round 6-2, 6-1.
This is the second time the Tay Ninh-born player has entered the second round of the men’s singles at the ATP Challenger tournament system.
The victory earned him eight points to the ATP ranking, as well as US$1,705. Previously, he gained five points after passing the qualifying round.
Nam’s opponent in the second round, held today, is sixth seed Daniel Brands of German (ATP 230), who has won six championships in ATP Challenger.