By RACHEL COHEN
NEW YORK (AP) - Kei Nishikori could tell from all the messages on his phone that the fans back home in Japan were watching in the middle of the night.
The 24-year-old stunned top-ranked Novak Djokovic 6-4, 1-6, 7-6 (4), 6-3 in stifling heat Saturday at the U.S. Open to become the first man from Asia to reach a Grand Slam singles final.
"Very happy to make history," he said.
Nishikori had played five-set marathons in his last two matches totaling more than 8 1/2 hours, yet he looked far fresher than a player known as one of the fittest on tour.
"He just played better in these conditions than I did," Djokovic said.
Under coach Michael Chang, the 1989 French Open champ, Nishikori has sharpened his mental game to pull out victories like these.
"He's matured a lot mentally here," Chang said.
Chang is a "tough" coach, Nishikori said.
"But I sometimes needed something," he added. "Some people can push me well, and it's been working really well."
The 10th-seeded Nishikori will face Roger Federer or Marin Cilic in Monday's title match.
Earlier, the midday sun beat down on Arthur Ashe Stadium and a thermometer on court showed the temperature nearing 100 degrees (37 Celsius), not counting the humidity of close to 70 percent. Nishikori closed this one out in 2 hours, 52 minutes.
Djokovic, who had reached the last four U.S. Open finals, outlasted two-time major champ Andy Murray in four long, tough sets in the quarters. But he never looked comfortable Saturday and spent much of the match scrambling around the court as Nishikori dictated points.
"Just wasn't myself," Djokovic said.
In the third-set tiebreaker, Djokovic had four unforced errors and a double-fault. Nishikori then broke to open the final set, and Djokovic wasted three break points in the next game.
Nishikori converted 5 of 7 break points, while Djokovic was just 4 for 13.
"Other than that second set, my game today was not even close to what I wanted it to be," Djokovic said. "A lot of unforced errors, a lot of short balls."
Chang, the New Jersey-born son of Taiwanese immigrants, knows a thing or two about groundbreaking victories. At age 17, he became the youngest man to win a Grand Slam title when he upset Ivan Lendl and Stefan Edberg (now Federer's coach) at Roland Garros.
"I will continue to remind him tomorrow: The work's not done," Chang said. "We've got one more match to go. And we'll prepare as best we can."
A severely infected right big toe forced Nishikori to miss tuneup events before the U.S. Open, and he feared that his lack of conditioning would make for a short stay at Flushing Meadows. Instead, he keeps sticking around - on the court and in the tournament.
"I didn't even know if I should come to New York, so I was expecting nothing, actually," he said. "But after playing first match and second match, I get more confidence on my foot."
He added with a grin: "I may have to rest three weeks before the (next) Grand Slam."