Japan's Kei Nishikori, back on form after a torn right wrist tendon, returns to the scene of his most recent outdoor title hoping to launch another strong US Open run.

The 28-year-old seventh seed enters the 50th Washington Open with confidence after his first Wimbledon quarterfinal appearance, where he lost to eventual winner Novak Djokovic.

“After coming back from injury, I'm enjoying the challenge this year. I feel like I'm going to be tough again. My wrist is OK now. I'm going to try and get into the top 10 again. That's my goal and motivation,” Nishikori said on Monday.

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World number 20 Nishikori, who beat John Isner in the 2015 Washington hardcourt final, has not won a title since taking the 11th of his career at Memphis in 2016. He has lost his past seven ATP finals, most recently in May to Rafael Nadal at Monte Carlo.

Nishikori reached a career-best fourth in the rankings in 2015, but tumbled during his six-month ATP wrist injury layoff. This year, he has started to rebuild his ranking.

“Feeling great again. Had a couple days off after Wimbledon and started working again. I'm trying to keep my intensity up. I got a little confidence going to the final at Monte Carlo. Still, I feel it sometimes, but most of the time, I'm feeling great. Now, I'm enjoying playing tennis again,” Nishikori said.

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Nishikori's best results in 32 Grand Slam appearances have come at the US Open, a runner-up showing behind Marin Cilic in 2014, and a 2016 semifinal loss to eventual champion Stan Wawrinka.

He also has reached three Australian Open quarterfinals and two French Open quarterfinals. Nishikori received a first-round Washington bye and will face either US qualifier Donald Young or Swiss wild card and three-time Grand Slam champion Wawrinka in his opener.

“Both players are tough. I'm going to have to play focused from the first match,” Nishikori said. The Asian number one worked out Monday with his top rival for the spot, 23rd-ranked Chung Hyeon of South Korea.

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“I'm very honoured to be the number one Asian and Japan player. I don't feel any pressure from being number one in Asia. My goal is to be number one in the world,” Nishikori said.

Nishikori praised 287th-ranked countryman Yosuke Watanuki, a 20-year-old, who battled through qualifying to reach his first ATP main draw.

“He has a great forehand, maybe better than me. I hope he does well. He's playing great enough to be top 100. Hopefully, he does a big jump this summer,” Nishikori said.