Here is a list of Sithmorseng's best fights. For a list of Sithmorseng's losses, refer to "Kwanthai Sithmorseng Losses".
On April 29, 2008 Kwanthai Sithmorseng faced off against Zhang Yuan Boau in a strawweight bout at age 23. He was coming in with a record of 18-0-1 (10). Sithmorseng stopped Zhang Yuan Boau via TKO.
On November 1, 2007 Kwanthai Sithmorseng faced off against Adisak Polkratok in a strawweight bout at age 23. He was coming in with a record of 15-0-1 (9). Sithmorseng stopped Adisak Polkratok via KO.
On May 22, 2012 Kwanthai Sithmorseng faced off against Hengky Elleuw in a strawweight bout at age 27. He was coming in with a record of 35-1-1 (19). Sithmorseng stopped Hengky Elleuw via TKO.