In 2020 Petchthongchai was announced as one of the eight contestants in the 31st Isuzu Cup happening at 138 lbs and taking place at the Omnoi Stadium.
[2] Petchthongchai faced Hercules Wor.Jakrawut on February 13, 2021, as part of the group stage of the Isuzu Cup.
[10] In 2023 Petchthongchai entered the Rajadamnern World Series tournament in the Super Lightweight division.
On July 15, 2023, Petchthongchai defeated Sakulchailek Pangkongpap by unanimous decision for his last group stage match and qualified for the Final 4 of the competition.
[12] On October 30, 2023, Petchthongchai faced Siwakorn Kiatcharoenchai at a Muay Thai Pantamit + Sor.Salacheep promotes event in the Lopburi province.
[15] On December 7, 2024, Petchthongchai faced Dam Parunchai for the third time in the final of the 2024 Rajadamnern World Series 140 lbs tournament.