Promising Bulgarian Grigor Dimitrov, ranked 76th in the world, ousted the fifth-seeded Croatian Dodig 6-2, 7-5, while Thai wild card Danai Udomchoke topped the sixth-seeded Italian Fognini 6-4, 3-6, 6-2 on the hardcourts at Impact Arena.
Seventh-seeded Dutchman Robin Haase avoided an upset by handling Thai wild card Kittipong Wachiramanowong 6-3, 7-6 (7-1), while one other Day-1 result saw Colombian Santiago Giraldo ground Israeli Dudi Sela 6-2, 6-3. Giraldo will meet second-seeded French star Gael Monfils in the round of 16.
Guillermo Garcia-Lopez is the reigning Bangkok champion, having beaten Finn Jarkko Nieminen in last year's finale. Garcia-Lopez stunned his fellow Spaniard Rafael Nadal in the semifinals here a year ago.
The 2011 Bangkok titlist will earn $107,000.