Kei Nishikori reaches U.S. Open final, beating Novak Djokovic and becoming the first man from Asia to reach a Grand Slam final.

Kei Nishikori of Japan won in four sets on Saturday at the U.S. Open.

As Kei Nishikori has kept fighting through imposing obstacles at this United States Open, his coach Michael Chang has kept reminding him, “Great effort, but the tournament is not over yet.”

It certainly is not. After fighting his way through consecutive five-set matches to earn a semifinal spot against No. 1-seeded Novak Djokovic, Nishikori extended his one-man show of resilience by upsetting Djokovic to reach the final.

His remarkable 6-4, 1-6, 7-6 (4), 6-3 victory on Saturday made him the first man from Asia to reach a Grand Slam singles final.

It’s, I don’t know, 4 o’clock in the morning,” Nishikori, 24, said of the time in his native Japan. “But I hope a lot of people are watching.”

If they were not on Saturday, they will be soon. Nishikori, who left home at age 14 to train at the IMG Academy in Bradenton Fla., was a star in his homeland. His run here and his victory over Djokovic will take him to a new level.

I was a little bit tight,” Nishikori said, “especially it was my first semifinal in a Grand Slam, but it’s just amazing, amazing feeling beating the No. 1 player.”

In Monday’s final, Nishikori will face the winner of Saturday’s second semifinal between No. 2-seeded Roger Federer and No. 14 Marin Cilic.

The 10th-seeded Nishikori is the lowest seed to reach the final of the United States Open since Pete Sampras, who was seeded 17th when he won the title in 2002 in what turned out to be his final professional match. But Nishikori is just getting started and might well have made this kind of breakthrough earlier if not for a series of injuries, including a serious right elbow problem that required surgery in 2009 and knocked him far out of the top 100.

He has long been considered a great talent by people who have seen plenty of great talent, including Nick Bollettieri, the veteran American coach who is the instructor emeritus at the academy in Bradenton that once bore his name.

He and Xavier Malisse and Marcelo Rios are the best shotmakers I’ve ever worked with,” Bollettieri said in an interview before this season. “If Kei Nishikori could stay healthy, he could be and would be right up with the big boys.

Eight months later, there he was in Arthur Ashe Stadium beating the top-ranked player in the world. Nishikori had played Djokovic twice before; losing in the second round of the French Open in straight sets in 2010, and upsetting him in 2011 near the end of Djokovic’s finest season in the semifinals of the indoor tournament in Basel, Switzerland.

But this was certainly a much grander stage than Basel, and what made his victory all the more remarkable was that Nishikori had spent nearly three and a half hours longer on court in this tournament than Djokovic coming into this semifinal.

Nishikori needed five sets and more than four hours to beat fifth-seeded Milos Raonic in a fourth round that ended at 2:26 a.m. Tuesday. He did not get to bed until close to 6 that morning but then bounced back on Wednesday to upset third-seeded Stan Wawrinka, the reigning Australian Open champion, in five sets.

Before he played Stan, I was more concerned that he would still be focusing on the Raonic match,” Chang said. “So I was like constantly telling him, ‘Hey you’ve got another match here to play, another match, another match.’ Because that tends to be the struggle with players that have a big win and then a letdown following that.”

Chang, the American who shocked the tennis world to win the 1989 French Open at age 17, began coaching Nishikori this season, joining a team that included his coach Dante Bottini and the fitness trainer Hiroto Kon.

He’s been helping me a lot,” Nishikori said of Chang. “Him and Dante communicating a lot, and it’s been working super well, so that’s why I’m here.”