NEW YORK (AP) — Japan’s Kei Nishikori became the first man from Asia to reach a Grand Slam final, stunning top-ranked Novak Djokovic 6-4, 1-6, 7-6 (4), 6-3 in stifling heat Saturday at the U.S. Open.

“It’s just amazing, an amazing feeling beating the No. 1 player,” Nishikori said in an on-court interview.

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He 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.

“I guess I love to play long matches,” he said with a grin.

Under coach Michael Chang, the 1989 French Open champ, the 24-year-old Nishikori has sharpened his mental game to pull out victories like these.

“We’ve been working super well,” Nishikori said of Chang and co-coach Dante Bottini. “That’s why I’m here.”

The 10th-seeded Nishikori will face Roger Federer or Marin Cilic in Monday’s title match, though rain was delaying the start of the second semifinal.

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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.

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.

In the third-set tiebreaker, Djokovic had four unforced errors and a double-fault. Nishikori then broke him 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.

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