While Liverpool boss Jurgen Klopp named an understrength and inexperienced starting XI, new Man United boss Erik ten Hag sent arguably his strongest available side onto the field.
The Red Devils took the lead in the 12th minute of the contest when Jadon Sancho expertly fired home from inside the penalty area, before Fred doubled their advantage in the 30th minute, brilliantly chipping Liverpool goalkeeper Alisson Becker after the ball had fallen kindly for the Brazilian.
Liverpool boss Klopp responded by making 10 changes in the 32nd minute, with Joel Matip, James Milner and Curtis Jones among those to enter the field for the Reds.
Man United had a third less than one minute later, though, when Anthony Martial, who was picked through the middle in the absence of Cristiano Ronaldo, raced through on goal before brilliantly firing past Alisson.
Liverpool made just one change at the break, with Adrian replacing Alisson, but there were 10 alterations for Man United, including a debut for Tyrell Malacia, who has arrived at the club from Feyenoord this summer.
Anthony Elanga, Donny van de Beek and Eric Bailly were also among those to enter, while Charlie Savage and Zidane Iqbal made strong contributions off the bench.
There were 10 more changes for Liverpool just past the hour, with the majority of their key players being introduced, including Mohamed Salah, Virgil van Dijk, Trent Alexander-Arnold and Andrew Robertson.
There was also a debut for Darwin Nunez, who passed up a brilliant chance to score when he somehow missed the goal from close range in the final exchanges of the contest.
Fellow debutant Fabio Carvalho and January arrival Luis Diaz also struck the post for Liverpool during the contest, with Man United's defence picked apart at times, but it was an overwhelmingly positive start for Ten Hag.
Man United also needed their goalkeeper David de Gea to make a string of impressive saves, while Salah fired onto the post in the latter stages, with Liverpool, unsurprisingly, improving when the majority of their big hitters were on the field.
De Gea had to be replaced in the 68th minute of the contest after picking up an injury, with Tom Heaton - now number two after Dean Henderson's departure - entering the field.
Man United were not finished in terms of the scoresheet, though, and made it 4-0 in the 76th minute when Facundo Pellistri brilliantly picked out the back of the net after smart work from Amad Diallo.
Bailly's charging run from the back was the main talking point for the fourth goal, and it proved to be just about the perfect start for Ten Hag in Thailand.
Man United will now head to Australia for matches against Melbourne Victory, Crystal Palace and Aston Villa, while Liverpool are next in action against Palace in Singapore on Friday.