Thailand national team coach Masatada Ishii has called up Korawit Tasa and Kakana Khumyok to replace injured forward Supachai Chaided and playmaker Supachok Sarachart.
Supachai scored a goal in Buriram United's 3-0 victory over Nakhon Pathom United in a Thai League 1 game on Sunday night but was injured afterwards.
Consadole Sapporo's Supachok was injured during a J-League 1 match with Kawasaki Frontale on Sunday.
Thailand are scheduled to take part in a three-nation tournament in Hanoi from Sept 5-10. Russia are the third team participating in the event.
On Sunday night, defending champions Buriram moved two points ahead of Port after an impressive show against Nakhon Pathom.
Supachai, Sasalak Haiprakhon and Chrigor scored for the Thunder Castle as they captured three points for the fifth game in a row for a total of 15 points.
Meanwhile, Ratchaburi shared a point with Port at their home ground after a 2-2 draw on Sunday night.
Port saw Willen Mota strike in the eighth minute, but the hosts rallied with a double from Tatsuya Tanaka (22, 47). Port equalised five minutes after the break through Bordin Phala.
Also on Sunday night, BG Pathum United routed Khon Kaen United 3-0 and Bangkok United edged Lamphun Warriors 3-2.