The Thai won his men's lightweight preliminary clash against Fiji's Jone Davule by unanimous decision, as the Buenos Aires 2018 champion began his route to Japan.

Elsewhere on day one here, there was disappointment for Jordan's home boxer Hisham El-Simreen who went down to Fanat Kakhramonov of Uzbekistan at middleweight.

The Uzbeks topped the medal table at the Rio 2016 Olympics and at last year's Men's World Championships, and Kakhramonov was always in control as he claimed a unanimous decision victory.

"I am disappointed but came up against a very good fighter," said El-Simreen.

Chinese boxers recorded three victories, including a win for Jun Shan in the lightweight class against Iraq's Hayder Karaawi.

Tanglatihan Tuoheta Erbieke was too strong for Mahmood Ui Hassan of Pakistan at middleweight and Daxaing Chen saw off Ehsan Rouzbahani of Iran at light-heavyweight.

Yong Chang was China's sole boxer to taste defeat as he lost by split decision to Sangmyeong Ham of South Korea in the featherweight.

India enjoyed a good day with two victories in the opening session.

Kumar Ashish defeated Chia-Wei Kan of Chinese Taipei at middleweight and Gaurav Solanki ousted Akylbek Esenbek Uulu of Kyrgyzstan in the featherweight class.

Uzbekistan also enjoyed a winner in women's boxing as Yodgoroy Mirzaeva got the better of Micronesia's Jennifer Chieng in a featherweight bout.

Australia had two winners with Kirra Ruston stopping Hong Kong's Leong Tai Kan at middleweight in his first international bout.

"I felt really good out there," he said.

"I caught him with a couple of good punches and felt really strong."

Ruston's team-mate Paulo Aokuso beat Navosa Ioata of Tuvalu in a light-heavyweight contest.

Olympic hosts Japan endured a tricky start as the country lost two contests.

Ren Umemura was defeated at light-heavyweight by New Zealand's Jerome Pampellone and Hayato Tsutsumi lost in the featherweight to Ian Bautista of The Philippines. 

There was success for Japan's Yuito Moriwaki at middleweight as he beat Muntadher Al-Farttoosi of Iraq.

More preliminaries will be held in Amman tomorrow.

The event was initially due to take place in Chinese city Wuhan, but was relocated due to coronavirus.

Thirty-five countries and 221 boxers are competing at the event, with 41 men's and 22 women's berths up for grabs at the Olympics.