The U.S. Open finalist clinched the first set via a tiebreak before the big-serving Raonic, who sent down 22 aces in the match compared to his opponent's one, roared back into the contest to force a decider.
The pair held firm on their serve until Nishikori got a crucial break in the 10th game to repeat the outcome of the 2012 Tokyo final in two hours and 13 minutes.
"It has been incredible and I think this is the first time I have won two weeks in a row," said Nishikori, who has been troubled by hip and lower back problems this week.
"After the U.S. Open, it was hard to maintain the motivation. Being the first final of a grand slam was my dream so it was tough to change mentally," said the 24-year-old, who won the Malaysian Open last week.
This was Raonic's third successive defeat in the final of the tournament, while the win put Nishikori fifth in the race to the season-ending ATP Finals in London, which will feature the top eight players.
"I'm getting close (to making the ATP Finals) but there are two more Masters and one more 500, so these three weeks are going to be really important for me," said Nishikori, who had tears in his eyes when he hugged coach Michael Chang.
RAONIC DISAPPOINTED
With Typhoon Phanfone advancing towards Tokyo, organisers closed the retractable roof in what was a rematch of a marathon U.S. Open fourth round duel that equalled the record for the latest match ever played at the year's final grand slam.
Nishikori outlasted Raonic 4-6 7-6(4) 6-7(6) 7-5 6-4 in four hours and 19 minutes at the Arthur Ashe Stadium before going on to become the first Asian male to reach a grand slam final.
On Sunday, Raonic showed the same fight by claiming the second set in 44 minutes, playing closer to the baseline, but Nishikori once again proved superior in the end.
"It is disappointing to lose in my third straight (Tokyo) final," Raonic lamented. "To be honest with you, other than the first year (2012), I felt I created my opportunities.
"Against Kei, he just played better when it came down to the third set. I have felt I have always been in the thick of things the past two years, so I would say two years ago was more disappointing."
(Reporting by Amlan Chakraborty; Editing by John O'Brien)
Share
