No manager likes to lose, especially their first game for a new club, and in this instance, replacing a man who served for 26 years and won 13 Premier League titles.
But Moyes can take several positives from this first run-out, as Adnan Januzaj in the first half and Wilfried Zaha - following his introduction in the second - impressed hugely.
And with Robin van Persie among those set to link up on Sunday in Sydney, where United will spend a week in rather cooler temperatures, the Scot can at least start to feel the hard work has begun in earnest.
It was a rather understated opening, though. With conditions more stamina-sapping than at any stage since United arrived in Thailand on Thursday morning, the Red Devils wisely adopted a cautious approach to the first match of an eight-game pre-season campaign building towards that Premier League opener at Swansea on August 17.
The one player with energy and incentive was 18-year-old Januzaj. Latest off that impressive Belgian production line, one of Sir Alex Ferguson's last acts as United manager was to give Januzaj a squad number, and also a place on the bench for that emotional final game at West Brom.
With Nani and Ashley Young both missing the tour completely and Antonio Valencia not due to join up until later, Januzaj has a chance to impress. And he certainly did so, with his direct running causing huge problems for the Singha All Stars defence.
He might well have scored too, only to side-foot a first-time effort over from close range after Tom Cleverley had crossed from the right.
Teeratep had already proved to be something of a nuisance for a side made up of the best players in the Thai league.
And five minutes after the restart he put the hosts ahead, driving deep into the United box before beating Ben Amos after two earlier failures.
Zaha's introduction just past the hour mark threatened to liven proceedings up a little.
Ferguson's final signing, Zaha completed the season by guiding Crystal Palace back into the top flight and he started his United career with intent, darting down the right flank on a couple of occasions before drilling over dangerous low crosses that ultimately brought no reward.
Danny Welbeck dragged a good chance wide before Zaha came closest to nicking an equaliser, cutting inside the box and curling a shot against the far post.