Momota was the overwhelming favourite against the world number 29, competing in his first major final, and justified his billing with a comfortable 21-14, 21-11 triumph at the Musashino Forest Sports Plaza.

The result saw the Japanese player continue his remarkable comeback after he served a year's ban for illegal gambling which kept him out of the Rio 2016 Olympics, as he added the Japan Open crown to the world title he clinched earlier this year.

He also managed to avoid what would have been a huge upset had Phetpradab capped off his superb performance at the event in the Japanese capital with a shock victory.

"I never thought I would stand here as champion," said Momota. 

"Thanks to everyone for the support. 

"I'm so glad I could show how much I've improved and it's a dream to be a winner here."

While there was a comfortable winner in the men's final, the opposite was true in the women's gold medal match as Olympic and world champion Carolina Marin battled past Japan's eighth seed Nozomi Okuhara in three games.

Marin needed one hour and 14 minutes to seal victory as  the Spaniard recorded a hard-fought 21-19, 17-21, 21-11 success over the home favourite.

Yuki Fukushima and Sayaka Hirota defeated Asian Games champions Chen Qingchen and Jia Yifan of China 21-15, 21-12 in a repeat of the 2017 World Championship final to secure the women's doubles title for Japan. 

In the men's doubles final, top seeds Marcus Fernaldi Gideon and Kevin Sukamuljo of Indonesia ousted second seeds Li Junhui and Liu Yuchen of China 21-11, 21-13.