Linh is currently ranked 49th in the world, eight places lower than Qi. But during the game, it only took her 34 minutes to win both sets 21-11.
"I'm really happy and emotional with this victory. Before the game, me and the coach had studied the opponent carefully to find a proper strategy. The result today made up for the difficulties I have faced for over a year," Linh said after the game.
"The opponent likes to deliver powerful, direct hits so I intentionally played more defensive to stop them. After that, I made use of quick attacks to score," Linh added.
The 24-year-old is in group P with Taiwan’s Tai Tzu-ying, Qi Xuefei and Swiss player Sabrina Jaquet.
In the next game on Monday, Linh will face world number one Tai, a heavy contender for the gold medal.
Only the top player from each group would advance to the next round.