Thanongsak Simsri (, born 17 June 2000), also known by his ring name Petchkoson Greentsuda (เพชรโกศล กรีนสึดะ) is a Thai professional boxer who has held the International Boxing Federation (IBF) light-flyweight title since June 2025. He is Thailand's 50th world boxing champion and the third to hold this weight class title in this organization, following Muangchai Kittikasem in 1989 and Saman Sorjaturong in 1995.

Early life He was born in Sisaket province and began boxing Muay Thai at the age of 14, driven by passion for the martial art. At 19, he decided to move to Bangkok to seek new opportunities. Due to his precise and swift punching skills, he caught the attention of scouts, which led him to switch from Muay Thai to professional boxing.

Professional career Early career Simsri made his debut on 20 June 2018 against fellow debutant Thanapong Saekoo in Samut Prakan, Simsri won via first-round TKO.

Simsri was scheduled against the reigning WBA and The Ring light-flyweight world champion Hiroto Kyoguchi for Kyoguchi's third title defense on 3 November 2020, Simsri was at the time the eleventh-ranked contender in the WBA light-flyweight rankings. On 2 November 2020, one day before the fight, Kyoguchi announced he was unable to fight, as both he and his coaches had contracted COVID-19.

Simsri vs. Yabuki After composing a record of 24–0, on 10 September 2022, Simsri fought former WBC light-flyweight world champion Masamichi Yabuki in what was promoted as a world title prelude for Yabuki, the fight was scheduled for a catchweight of 50 kilograms. Simsri lost the bout via seventh-round technical knockout, Yabuki knocked his opponent down twice prior to the stoppage, in the second and sixth rounds.

OPBF light-flyweight champion Simsri vs. Fajardo On 13 April 2024, Simsri challenged the knockout-artist and reigning OPBF light-flyweight champion Miel Fajardo for Fajardo's first title defense, the bout was held in Edion Arena, Osaka, Japan, Simsri prevailed via unanimous decision, thereby becoming the new OPBF champion, Simsri was down once in the tenth round prior to the decision-announcing.

Simsri vs. Taniguchi On 15 December 2024, Simsri made his third title defense against former WBO mini-flyweight world champion Masataka Taniguchi in Sumiyoshi Sports Center, Osaka, Simsri successfully defended the title via split decision.

IBF light-flyweight championship Simsri vs. Araneta As Masamichi Yabuki vacated the IBF light-flyweight world championship to campaign at the flyweight division, No. 1 IBF-ranked knockout artist Christian Araneta is set to face No. 2 ranked Simsri for the vacant IBF light-flyweight world championship. On 26 April 2025, it was confirmed that their bout was finalized and will take place on 19 June 2025 at the Ota City General Gymnasium in Tokyo, Japan. Simsri defeated Araneta via split decision to become new IBF light-flyweight world champion, Simsri was in control of the early stages but was dropped in the third-round by a counter left hand, Simsri stood up and quickly adjusted, and later controlled most of the bout to win decisively.

After winning the world championship, Simsri dedicated the title to his grandmother, who had died just two days earlier, shortly after he had celebrated his 25th birthday.

Simsri vs. Mendoza On April 13, 2026 (Songkran Day in Thailand), at Korakuen Hall in Tokyo, he made his first title defense by defeating the 26-year-old world No. 1 contender Sergio "Yoreme" Mendoza of Mexico via TKO (referee stoppage) in the second round, after Mendoza had previously been knocked down and given an eight-count. The victory ended Mendoza's winning streak at just 26 fights, with the bout concluding much more quickly than expected.

Simsri vs. Vicelles On September 26, 2026, Simsri defeated Mark Vicelles by 2nd round TKO to retain his IBF light flyweight title. Before the stoppage, he had twice sent the Filipino challenger to the canvas for eight counts, both times with straight right hands.

Personal life Although Simsri fights under the Japanese promoter Green Tsuda, which is based in Osaka, he lives and primarily trains in Thailand. He only travels to Japan when a fight is scheduled.

Professional boxing record

ResultRecordOpponentTypeRound, timeDateLocationNotes42Win41–1Mark VicellesTKO2 (12), 26 Sep 202641Win40–1Sergio MendozaKO2 (12), 13 Apr 202640Win39–1Christian AranetaSD1219 Jun 202539Win38–1Songchai SongklodKO3 (6), 22 Feb 202538Win37–1Masataka Taniguchi1215 Dec 202437Win36–1Saravut RongpigTKO2 (8), 5 Oct 202436Win35–1John Paul GabunilasTKO5 (12), 4 Aug 202435Win34–1Assada RakmitKO2 (6), 1 Jun 202434Win33–1Miel FajardoUD1213 Apr 202433Win32–1Bordin ChomphooTKO1 (8), 16 Dec 202332Win31–1Chiraphan TaosuwanTKO2 (8), 20 Oct 202331Win30–1Shota AsamiKO2 (8), 6 Aug 202330Win29–1Nawamin KlaypeayoonTKO1 (8), 18 Jun 202329Win28–1Oatsadin ThimthepTKO3 (6), 9 Apr 202328Win27–1Weerawat ThongchaichanTKO2 (6), 19 Feb 202327Win26–1Chiraphan TaosuwanTKO5 (8), 18 Dec 202226Win25–1Sittipon SangteanTKO3 (8), 20 Nov 202225Loss24–1Masamichi YabukiTKO7 (10), 10 Sep 202224Win24–0Kris SriphumTKO3 (8)24 Jul 202223Win23–0Jaturong YuenyongTKO2 (8), 1 May 202222Win22–0Benjaphon PhokamTKO2 (8), 27 Mar 202221Win21–0Kampanart ValsiripattanachaiTKO4 (6), 5 Feb 202220Win20–0Natthapon BuasaTKO2 (6), 19 Dec 202119Win19–0Songkran SosahwatTKO1 (8), 31 Oct 202118Win18–0Chanon SonkhamKO3 (8), 26 Sep 202117Win17–0Thaweesak NakhamTKO3 (8), 18 Jul 202116Win16–0Tongthep Taeyawong4 (8), 6 Jun 202115Win15–0Nutthakorn SungseveeTKO3 (6), 19 Mar 202114Win14–0Suriya PuttaluksaTKO4 (6), 6 Feb 202013Win13–0Christian BacolodUD88 Dec 201912Win12–0Lerdchai Chaiyawed612 Oct 201911Win11–0Nattee ThongsingcleKO3 (8), 31 Aug 201910Win10–0Mektison MargantiKO3 (8), 4 Aug 20199Win9–0Watcharaphon ChaisaiTKO2 (8), 15 Jun 20198Win8–0Panuwat YakaretTKO1 (6), 19 May 20197Win7–0Ricardo SuenoTKO1 (6), 21 Apr 20196Win6–0KermooKO1 (8)5 Feb 20195Win5–0Phirom Padanprasert5 (6)14 Dec 20184Win4–0Manop AudomphanawariTKO5 (6), 21 Nov 20183Win3–0Suriya PuttaluksaTKO2 (4), 12 Sep 20182Win2–0Prajak ButsreeTKO2 (4), 2 Aug 20181Win1–0Thanapong Saekoo1 (4), 20 Jun 2018

See also List of male boxers List of world light-flyweight boxing champions

References

External links