GUANGZHOU Last year, AlphaGo, a computer program developed by Google to play the ancient Chinese board game Go, stunned the world by beating the South Korean professional player Lee Se-dol. Now, 19-year-old Ke Jie may be humanity's best hope of regaining dominance over the machines.

"Without doubt, he is the world's best Go player," Yuta Iyama, a professional player who was the first person to hold all seven major Japanese Go titles simultaneously, said of Ke, who in December won the 2016 Samsung Cup, his fourth international title.

Ke was born in 1997 in a mountain town in central Zhejiang Province, China. His parents both worked and belonged to China's middle class, which was expanding fast amid the country's rapid economic growth. Ke began learning how to play Go at the age of 7, when his father brought him to a nearby Go center, where he instantly became fascinated with the game.

Young Ke visited his first master, Zheng Yibing, at his house almost every day and spent hours playing the game with him, over and over. He did not want to go home until he defeated his master. Ke developed his skills quickly, and after about a year, the adults around him, including Zheng, found they were no longer any match for him. Zheng told him, "I'm sorry, but I have nothing to teach you anymore, so you should go to Beijing."

Ke followed the advice, leaving his hometown by himself at the age of 8 to study Go in the Chinese capital. There, he devoted himself completely to the game, staying in a Go center night and day. At age 11, he became the youngest professional Go player ever in China. His mother, Zhou Liuping, quit her job and went to Beijing to look after her son.

"Because China was still a low-income country in the 1970s and 1980s, when I was born and brought up, we had no way to determine our own lives," Ke's mother said. "Accordingly, I want to help my son live his life the way he wants to."

The two lived in a tiny basement room, measuring less than 10 sq. meters. At first, Ke lost many games, and his mother repeatedly urged him to go back to their hometown. But he never gave up. After struggling for 10 years, he won his first international title at the age of 18.

Last year, Ke amassed more than $870,000 in total prize money. The rising star of Go bought a condominium in the heart of Beijing and brought his father there to reunite the family. He is, for the most part, a typical contemporary young man who wears a gold bracelet and loves playing games on his smartphone. But when it comes to the game of Go, Ke is completely obsessed, saying he dreams about it every night.

Before AlphaGo's victory last year, humans were expected to remain superior to the computer program for the foreseeable future. After the match, Ke said confidently that AlphaGo cannot beat him.

A specialized online ranking site showed that Ke is the world's number one Go player at the moment, with AlphaGo ranked second. However, his AI opponent is honing its skills by playing game after game against itself.

Discussing his plan for beating AlphaGo, Ke spoke in an uncharacteristically cautious manner.

"I am thinking of tactics that will allow me to gain an absolute victory over AI," he said.