Phước competed in the men's 200 m freestyle on 7 August. He and Ahmed Mathlouthi of Greece both finished last in the second group with a time of 1:50.39, and later shared the 41st position in the final ranking. On 6 August, Viên first competed in the women's 400 m individual medley, a category that she was well-trained and set the goal to reach the finals. With the finish time of 4:36.85, Viên came in first in the third group and broke her own national record set at the 2015 World Aquatics Championships in the category. Viên's result, however, was not enough to get her into the top eight swimmers in the final round; she ranked in 9th in the final ranking and only 0.31 seconds lower than the 8th ranking swimmer, Emily Overholt of Canada. The following day, she finished last in second group in the women's 400 metre freestyle event. With the finish time of 4:16.32, she ranked 26th out of 32 swimmers in the final ranking. Viên competed in the women's 200 m individual medley event on 8 August, where she finished at the penultimate position with the time of 2:16.20, only ahead of Uzbekistan's Ranohon Amanova, and ranked 33th out of 39 competitors in the final ranking.