Elahi Galan had no trouble disposing of Den Ouden in the first set, beating the Dutchman 6-1 and winning 13 of 16 service points. The Colombian 132nd-ranked player made optimal use of all three break points en route to his set win.
Den Ouden put up more of a fight in the second set, although it started rough for the Maarssen-born player with a break in his first service game of the set. After Elahi Galan fended off three break points in the third game, Den Ouden broke the Colombian with his fourth break point of the set.
The Dutchman fought till the end, but it wasn't enough as Elahi Galan broke Den Ouden in the twelfth and final game of the second set, thus clinching a 7-5 set win.
Den Ouden was the only other Dutchman to appear in the US Open besides Jesper de Jong, who beat Vilius Gaubas in straight sets in the first round.
Eva Vedder, Anouk Koeverman, and Arianne Hartono are set to play their qualifiers at Flushing Meadows on Tuesday evening. Arantxa Rus already progressed to the second round after beating Carlota Martinez Cirez on Monday.