Nishikori, who surged into prominence with his run to the U.S. Open final two years ago, said he is a better player now and buoyed by his strong showing at the Rio Olympics where he defeated 14-times slam winner Rafa Nadal to claim the bronze.
"I think I'm little more patient and playing much better than last year, two years ago. You know, I'm really excited for next week," the 26-year-old Japanese told reporters at Flushing Meadows.
"I feel a lot of special feeling here in the U.S. Open, a good memory from two years ago."
One year after he became the first Asian to reach a men's grand slam final, Nishikori in 2015 suffered a stunning first-round, five-set loss to 41st-ranked Benoit Paire of France.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Nishikori took the U.S. National Tennis Center by storm in 2014, beating Canada's Milos Raonic and third seed Stan Wawrinka in successive five-set struggles before ousting Novak Djokovic in the semi-finals.
He fell short of lifting the winner's trophy, however, as he fell to big-serving Croat Marin Cilic in the final.
Nishikori has enjoyed a fine hardcourt season, highlighted by a trip to the Toronto final and his appearance on the podium at the Rio Games to collect a bronze medal after a three-set win against 14-times slam winner Nadal.
"I had a great experience," he said. "Olympic games, it's something special, and especially the last match against Rafa I played good tennis.
"He almost came back, but played a great match. I had a lot of confidence from that match."
While Nishikori feels good about his game, he knows other prominent players are also hitting top form for the year's last grand slam championship, starting with top seed Djokovic and Wimbledon and Olympic winner Andy Murray, the second seed.
"I think those two guys are doing really well. I think Andy has a lot of chance to beat Novak," said sixth-seeded Nishikori.
"But I think a couple young guys, Raonic and Cilic, is back on track again. I think it's going to be a tough tournament."
Finishing runner-up to Murray in Rio was 2009 U.S. Open winner Juan Martin del Potro of Argentina, who is returning to top form after a long struggle with a wrist injury.
"I think he's the most dangerous unseeded player. He has great chance to win in grand slam," Nishikori said about del Potro, a wild card entry to the tournament.
Nishikori's first opponent will be unseeded Benjamin Becker of Germany.
"He has great serve, aggressive player. It's not going to be easy, but I hope I can have great preparation these few days and ready," said the Japanese.
(Editing by Andrew Both)
