Due to unpredictable circumstances, both matches will be held concurrently at 6.30pm (local time).
Cambodia will play Indonesia at the Phnom Penh National Olympic Stadium. Meanwhile, the Myanmar-Malaysia match, previously set to kick off at 3.30pm, will take place at the RSN Stadium, with a capacity of 5,000 seats.
In Group A, Vietnam ranked first after a goalless draw with Thailand on February 21.
Both of the teams had booked their spots in the semi-finals of the regional competition by winning against the Philippines and Timor-Leste.
The semi-finals of the tournament will be held on February 24. Thailand will play against Cambodia, who tops Group B, in the round. Vietnam will meet the runner-up of Group B.