Warit Sornbutnark lost in straight sets to Hong Kong’s Phillip King, 6-2, 7-6, 63, though he did manage to stretch the second set to a tie-breaker.
Despite being plainly fitter than the Chinese – and 12 years younger – Warit made many unforced errors, throwing away points to the steadier, more careful King.
In the afternoon the Thais did better, with Wishaya Trong Charoentraikul defeating Ognian Kolev in a tough match 6-4, 7-5, 7-5, to end the day with honours even.
The tournament at Thanyapura – which was moved from Bangkok because of the political turmoil in the capital, was opened in a brief ceremony chaired by Chart Pattana Party leader Suwat Liptapanlop, escorted by Thanyapura founder Klaus Hebben and Deputy Governor Jamroen Tippayaponhthada.
Governor Maitri Inthusut arrived later to watch the second half of the game.