
Thien, the first Vietnamese player to be allowed to take part in the Australian Open Tennis Tournament for U-18 players, crushed No 2 seed Indian Raman Rishabdev in the second round to secure a spot in the quarter-final.
This is the first time Thien, who ranks 238th in the world junior ranking, has advanced to the competition's semi-final.
"I am very happy with this result. It will help me play with more confidence in upcoming tournaments," said Thien.
Thien, who started playing tennis at the age of eight, hopes to reach the International Tennis Federation's top 100 junior ranking within the next two years.
VNS