Kovacevic upsets Kecmanovic in Seoul
American Kovacevic was only playing in the first round as a lucky loser in Seoul after he was beaten in the final round of qualifying, but he grasped his chance by winning 6-4 6-4.
The 24-year-old served 14 aces and broke the world number 32 three times to set up a second-round meeting with Christopher O'Connell or Tseng Chun-hsin.
Radu Albot got the better of Hiroki Moriya in his first appearance in Seoul, while Jaume Munar progressed when Yosuke Watanuki retired early in their match due to an ankle injury.
Kaichi Uchida came out on top in the final match of the day, consigning Hong Seong-chan to a 6-4 6-2 defeat.