In the decisive third game, the No. 1-ranked team from Japan rallied from a 19-16 deficit to clinch the country's first Olympic badminton gold.

Park, who has been coaching Japan since 2004, said while he was hoping for good results, he wasn't entirely convinced his athletes were ready to win a gold this year.

Both Matsutomo, 24, and Takahashi, 26, were making their Olympic debuts.

"I knew there was a possibility," he said. "I wanted them to gain experience here and try to win gold four years later at the Tokyo Olympics. But they did a great job here. This gold medal came four years ahead of time." 

Park is best remembered among South Koreans for winning the men's doubles gold medal in 1992, and then the mixed doubles silver in 1996. He boasts two world titles in the men's doubles and three more in the mixed doubles.

And his first gold as a coach with Japan has been 12 years in the making.

At the 2008 Beijing Olympics, Park's first as Japan's coach, Miyuki Maeda and Satoko Suetsuna reached the semifinals in the women's doubles. Then four years later, another women's doubles team, Mizuki Fujii and Reika Kakiiwa, won silver -- Japan's first Olympic badminton medal.

Japan may pick up another medal in Rio, with Nozomi Okuhara waiting to face Li Xuerui of China in the bronze medal match on Friday. Li suffered a leg injury in the semifinals against Carolina Marin of Spain.

Park, whose goal for Rio was to win two medals of any color, said, "I think we could win two medals as we'd hoped." (Yonhap)