Seventeen-year-old Nguyen Thi Anh Vien won gold with a new meet record in the women's 400 m medley at the SEA Games in Myanmar Monday.
She was too strong for her rivals and kept widening the gap after each lap, being more than 20 meters ahead of the second-placed swimmer after 300 m.
She completed the event in 4 minutes 46.16 seconds, beating the old record by a whopping 4.72 seconds.
She won three gold medals in all, breaking two games records in the process.
She is the first Vietnamese swimmer to win three gold medals in a single games.
Dinh Viet Hung, head of the swimming division at the General Department of Physical Training and Sports, said: "Anh Vien has made surprising progress. If she had not suffered from diarrhea two days ago, she could have won five gold medals."
Vietnam's top male swimmer, Hoang Quy Phuoc, won the 200 m freestyle in 1 minute 50.64 seconds from Malaysia's Henry Bego.
Vietnam won five gold, five silver, and two bronze medals from the pool, their best ever haul.
Elsewhere, Vietnam also won gold in mixed archery team and men's single archery, women's marathon, women's double scull, and men's team cycling.
The country won a total of 43 gold medals to be in second place behind Thailand, who have 59. Host Myanmar are third with 39.