Man Singh became only the second Indian man to clinch a gold medal at the Asian Marathon Championships as he won the race with a personal best time in Hong Kong on Sunday.
The 34-year-old Man Singh clocked two hours, 14 minutes and 19 seconds (2:14:19) to win the competition. His earlier best was 2:16:58, which he had clocked while finishing 11th in the Mumbai Marathon last year.
China's Huang Yongzheng took the silver with a time of 2:15:24 while Kyrgyzstan's Tiapkin Ilya came third in 2:18:18.
Another Indian in the fray, AP Belliappa finished sixth with a time of 2:20:20.
In the women's marathon race in Hong Kong, Ashvini Madan Jadhav finished eighth with a time of 2:56:42 while Jyoti Gawate ended at 11th in 3:06:20.
Gopi Thonakal was the first Indian man to win the Asian Marathon Championships title in 2017. He had clocked 2:15:48 to win the gold in Dongguan, China.
Man Singh's time on Sunday was below the Paris Olympics qualifying mark of 2:08:10. He had finished eighth in the Hangzhou Asian Games last year in 2:16:59.