Home star Kei Nishikori secured an impressive first round victory against Andrey Rublev in Tokyo, beating the fifth seed 6-3 6-4.
Ranked 69th in the world, the unseeded player will be the sole Japanese representative in the second round.
Marcos Giron of the United States awaits, having beaten Slovakian opponent Norbert Gombos 7-6 3-6 6-2.
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A win over such a high-profile opponent will surely serve as a huge boost to Nishikori, who will be looking to improve upon the bronze medal he won at Rio 2016.
"You know it's been a while playing like this and playing to beat top 10 players. I think it's been two years already," the 31-year-old told media.
"I was a little bit worried if I got nervous on the court but I wasn't, so that's a good sign."
Tokyo marks Nishikori’s fourth Olympics campaign, and he revealed that experience was vital in his win over the 23-year-old Russian.
He said: “I think experience helps a lot. The first Olympics (in 2008) I was really nervous, and I have a bad memory about that (after losing in the first round) but since then, I think I got many experience, I got strong mentally, and I'm playing good."
Nishikori now solely carries the Japanese flag in the men’s singles side of the draw, after Yoshihito Nishioka and Yuichi Sugita fell at the first hurdle.
Nishioka lost 6-3 1-6 2-6 to the Russian Olympic Committee’s Karen Khachanov, whilst Sugita was knocked out by Italian opponent Fabio Fognini 4-6 3-6.
There was joy to be found in the women’s event however, as cauldron lighter Naomi Osaka extinguished China’s Zheng Saisai 6-1 6-4 to safely progress to the second round.
The 23-year-old revealed she had some anxieties before the match, but a strong performance ensured she avoided an upset against the 52nd ranked Saisai.
She said: "I felt really nervous being in Japan, playing here for the first time in maybe two years, and for it to be my first Olympics.
“"It was definitely really nerve-wracking. But I am glad I was able to win."
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