PARIS (AP) -- Still not fully recovered from injury, ninth-seeded Kei Nishikori of Japan lost 7-6 (4), 6-1, 6-2 to 59th-ranked Martin Klizan of Slovakia in the first round of the French Open on Monday.
A year ago, Nishikori became the first Japanese man in 75 years to reach the fourth round at Roland Garros, before losing at that stage to eventual champion Rafael Nadal. This month, Nishikori became the first player from his country to be ranked in the ATP's top 10.
But he entered the clay-court Grand Slam tournament dealing with a problematic lower left back and said over the weekend he wasn't fully recovered despite taking time off tour to head home to Florida for treatment.
Nishikori is the first player seeded in the top 10 to lose at the French Open.
''Really disappointed,'' said Nishikori, who has been getting coaching help from 1989 French Open champion Michael Chang.
''I mean, I didn't have much practice. So, you know, I knew this is going to happen,'' Nishikori added Monday. ''I was playing well on clay in Europe, so it's very sad for me to lose first round here.''
The 24-year-old Nishikori was forced to pull out of the final of the clay-court Madrid Open against Nadal on May 11 because of his injury, ending a 14-match winning streak that included a title on clay at the Barcelona Open.
''First time playing points after Madrid, so I didn't have much rhythm,'' Nishikori said after losing to the left-handed Klizan. ''And also serve - I didn't hit any serve 100 percent before today.''
Nishikori already has dealt with a series of health issues during his professional career, including right elbow surgery in 2009 and an abdominal injury that forced him to skip the 2012 French Open.
''It's tough for me, but I guess this is my tennis life, you know. I have to take care of my body and injury will come again, for sure. So I have to mentally be ready,'' he said. ''I have to do whatever I can do to get healthy.''
Monday's victory was only the second of Klizan's career against a top-10 player.
''I just saw a little bit, sometimes, he was touching (his) back when he was serving,'' said Klizan, the 2006 French Open boys' champion. ''I think in the rallies he played very solid tennis.''