Japanese fans in Matsue watch the Nishikori match against Novak Djokovic

Japan’s social media lit up on Sunday as the country awoke to the news that Kei Nishikori had become the first Asian man to reach a Grand Slam singles final.

Nishikori completed a historic 6-4 1-6 7-6 6-3 victory over the world number one Novak Djokovic in New York in the early hours of the morning local time which public broadcaster NHK hailed as “an unprecedented achievement for Japan”.

The Nikkei Shimbun economic newspaper even updated its online homepage to carry news of the triumph.

Many bleary-eyed tennis fanatics had to watch live internet streams of the match — which began just after one o’clock in the morning Japan time and lasted close to three hours — with the action only available on television via a satellite subscription network.

Kei Nishikori: at a press conference after defeating Djokovic

One hardcore Nishikori fan, Minako Takigawa, 35, told AFP: “It’s so amazing. I stayed up to watch and still can’t sleep I’m still buzzing. I’ll be a nervous wreck for the final.”

TV commentators screamed themselves hoarse, yelling “Nishikori through to the final!” as the 24-year-old dropped his racquet after clinching match point before sheepishly ruffling his hair, scarcely able to believe the scale of his achievement.

In Nishikori’s hometown of Matsue in rural Shimane prefecture, some 300 fans cheered on their idol while watching on a giant screen, Nishikori retweeting a photo of them waving banners as he stormed to the biggest win in Japanese tennis history.

“I don’t care too much about history,” world number 11 Nishikori told local media.

“I might feel a bit nervous but I definitely believe I can keep this form going and go on to win it.”

Nishikori’s previous best Grand Slam performance had been reaching the last eight of the 2012 Australian Open, and not since Kimiko Date reached the Wimbledon semi-finals in 1996 had Japanese tennis witnessed anything close to Nishikori’s heroics in New York.

Should Nishikori overcome Croatia’s Marin Cilic in Monday’s final the impact on the sport in Japan could be potentially enormous — and it could not come at a better time with Tokyo set to host the 2020 Olympics.

“This is definitely huge for Japan,” said Wimbledon champion Djokovic.

China’s Li Na has put Asian tennis on the map in recent years but injuries have frequently hampered Nishikori’s attempts to fulfil his potential, until now.

Nishikori tweeted a picture of himself doing post-match media in a commentary box with American great John McEnroe, saying: “Amazingly happy with my win today. Always great to meet some legends.”