Datsakorn suffered a recurrence of an old groin injury during Thailand's 2-1 Group A defeat of the Philippines on November 24.
The talented Muangthong United midfield star was then forced to miss Thailand's two remaining group games which saw the War Elephants beat Myanmar 4-0 and Vietnam 3-1 to finish on top of the table.
Thailand coach Winfried Schafer has however revealed that he has no injury worries, and that his charges are ready for the challenge that will face them at Kuala Lumpur's Bukit Jalil National Stadium on Sunday.
"We do not have any injured players," the German declared.
"The atmosphere at training was fantastic.
We practiced several moves to be used against Malaysia," he added.
Three-time champions Thailand will host the return leg against Malaysia at the Supachalasai Stadium in Bangkok on December 13.
Singapore face the Philippines in the other last four encounter.
December 8, 2012
Philippines vs Singapore
December 9, 2012
Malaysia vs Thailand
December 12, 2012
Singapore vs Philippines
December 13, 2012
Thailand vs Malaysia