 In 2003, Therdsak led BEC Tero Sasana to the final of the AFC Champions League against Al Ain FC in 2003.He scored against Taejon Citizen and Shanghai Shenhua in the process and was named the 2003 AFC Champions League most valuable player.In 2004, Therdsak secured a move to Vietnam's East Asia Bank but did not settle well due to a stomach muscle injury which kept him out for seven months.