Yoshihito Nishioka knocked fifth seed Dan Evans out of the Korea Open with a straight-sets victory on Tuesday.
Nishioka moved into the second round in Seoul with a 6-2 7-6 (7-3) defeat of the Briton.
The world number 56 from Japan will face Taro Daniel or Emilio Gomez in round two after winning 70 per cent of points on his first serve and breaking Evans four times.
Jenson Brooksby was forced to go the distance, but delivered a final-set bagel as the eighth seed saw off Wu Tung-lin 7-6 (7-5) 3-6 6-0.
Qualifier Nicolas Jarry will take on top seed Casper Ruud after defeating Ryan Peniston 6-3 7-6 (10-8), while American duo Mackenzie McDonald and Steve Johnson also advanced.
Tseng Chun-hsin progressed with Chris O'Connell retired with an injury after losing the first set before Kwon Soon-woo beat Yunseong Chung in an all-South Korean contest.