NANJING - Kento Momota dedicated his world title on Sunday to those who stuck by him when a gambling scandal threatened to wreck the history-maker's budding career.

The explosive 23-year-old convincingly defeated China's highly promising Shi Yuqi 21-11, 21-13 in Nanjing, becoming the first Japanese man to win the World Championships. Carolina Marin claimed her own slice of history as the Spaniard became the first woman to win three badminton world crowns with an emphatic victory over PV Sindhu of India.

Momota's career descended into controversy in 2016 when Japanese badminton chiefs suspended him for more than a year for visiting an illegal casino, denying him a place at the Rio Olympics. Momota, number two in the world at the time, has been working his way back to the top ever since and was the pre-tournament favourite in Nanjing.

After dismissing Shi, Momota was coy about his temporary absence from the sport, but said after a pause: "There was a time when I was away. "But I got a lot of help and support from many people, this title is a good reward for them." Momota, now seventh in the rankings, said he wanted to emulate greats Lee Chong Wei and Lin Dan, two super stars who have reigned over badminton for well over a decade. Lee missed the tournament because of illness and Lin was well beaten by Shi in the third round. "They have had long and successful careers and like them, I want to give the audience enjoyment," said Momota, whose championship-winning point was a huge anti-climax -- the shuttlecock hitting the top of the net before falling in his favour.

The Japanese immediately apologised to Shi, who was playing in front of his home-province crowd and appeared nervous, making numerous errors. The third seed, 22, defeated compatriots Lin and Olympic champion Chen Long on the way to the final to confirm a changing of the guard in Chinese men's badminton. "That is why they call me the hope of Chinese badminton, but I need to improve on all fronts," he said modestly.

There were tears of joy from the 25-year-old Marin after her victory over the unfortunate Sindhu in the women's final. The aggressive Marin is now the reigning world and Olympic champion thanks to a ruthless 21-19, 21-10 win.

The all-action Spaniard adds the 2018 world crown to her titles in 2014 and 2015, and the Olympic gold she won at Sindhu's expense at Rio 2016. "I feel really happy, I cannot describe my emotions now, I have so many inside," said Marin, who was imperious all week despite being a modest seventh in the seedings.

Third seed Sindhu, 23, well known for her never-say-die spirit, has now suffered a string of near-misses. As well as disappointment at Rio, Sindhu was beaten in last year's World Championships final by Japan's Nozomi Okuhara and had to settle for silver at this year's Commonwealth Games too.

Sindhu said she could not live with the pace of Marin. "She has that speed. Today she started fast and I was prepared for everything," said the Indian, who owes her athleticism to volleyball-playing parents. She described another finals defeat as "frustrating and quite sad". "But I need to come back stronger," she said.

Aside from Marin, Japan and China dominated the last day of action. Mayu Matsumoto and Wakana Nagahara won the women's doubles title in a thrilling all-Japanese final, while the hosts took gold in the men's doubles and mixed doubles.