The pair have reportedly picked up minor knocks in training and are being rested as a precaution.
It is particularly disappointing for Garner, who was hoping to use the tour to convince new United boss Erik ten Hag that he is worthy of staying in the first team squad this season.
The Birkenhead-born midfielder has now missed the first two encounters on his return from an impressive loan spell at Nottingham Forest last term.
David de Gea is also missing after limping off in the 4-0 win over Liverpool on Tuesday in Bangkok.
Meanwhile, captain Harry Maguire is back in action after missing the Liverpool game with a minor niggle.
Maguire lines up alongside Victor Lindelof in an otherwise unchanged defence.
Neither player was at his best on Tuesday.
The full starting line-up is as follows:
Heaton, Dalot, Lindeloif, Maguire, Shaw, McTominay, Fred, Sancho, Fernandes, Elanga, Martial.
— Manchester United (@ManUtd) July 15, 2022
The match kicks off at 11.05am BST.