He lost in the final of the “Fuktien Group 8-Man Tournament 8-Man @146 lbs against Iquezang Kor.Rungthanakeat by TKO in the 5th round (broken collarbone) at Omnoi Stadium on 23 July 2011.

His first fight back after recovery from injury 5 months later was at the “A1 - WCC” event in Lyon, France on December 8, 2011, where he beat Fares Bechar by TKO in the fourth round.

[6][7][8] He won the “Toyota Vigo 8-Man Tournament” @70 kg against Dechrid Poptheeratham by decision after 3 rounds in Udon Thani on March 29, 2013.

It was reported that he would fight Kamel Jemel at the WBC World Muay Thai Millennium Championship in Saint-Pierre, Réunion on September 7, 2013.

[14] He took an extension round decision over Chingiz Allazov at Thai Boxe Mania in Turin, Italy on January 25, 2014.

[15] Sitthichai defeated Mohamed Khamal via UD at Legend 3: Pour Homme in Milan, Italy on April 5, 2014.

His last fight under Muay Thai rules to date was a victory against Crice Bousouko at 70 kg at the La Nuit des Titans 2015 event in Tours, France on February 7, 2015.

He had initially been set to face Davit Kiria on the main card but was demoted to the prelims when his opponent was changed.

[20] He won the “La Nuit des Champions” 4-Man Tournament (under K-1 rules) event in Marseille, France by defeating Abdellah Ezbiri in the final by TKO in the second round on November 22, 2014.

He won the Fight League - Grand Prix 8-Man tournament 70 kg by defeating Yasssin Baiter by KO in the second round in the Final in Tangier, Morocco on August 8, 2015.

He won via second round head kick KO to secure the Wu Lin Feng 71kg World Championship.

[31] Sitthichai would then face Marat Grigorian in the fourth meeting between the two on August 25, 2018, winning by split decision at Glory 57 in Shenzhen, China.

[35][36] Sitthichai was scheduled to make his ONE debut at ONE Championship: No Surrender on July 31, 2020, where was set to face Superbon Banchamek for a third time.

[43] Sitthichai faced Tayfun Özcan in the quarter-finals of the 2021 ONE Kickboxing Featherweight World Grand Prix at ONE Championship: First Strike.

[45] Sitthichai was scheduled to face Davit Kiria in the semifinals of the ONE Featherweight Kickboxing World Grand Prix at ONE: Only the Brave on January 28, 2022.