US Open 2019: An interactive timeline of defending champion Naomi Osaka's year since her breakthrough moment at Flushing Meadows

Everything felt better for Naomi Osaka once she returned to the US Open. The knee injury that forced her to retire during her last match no longer is so painful. The disappointment with her tennis that led her last month to say she wasn’t having fun playing has been replaced by calmness. When she comes back to Flushing Meadows, she’s a champion. And in many ways, she’s home. “Yeah, I mean, I feel like I have a familiarity,” Osaka said on Friday. “That’s not because I won last year. It’s because I have been kind of hitting on these courts since I was a kid. I used to train here.” All that training paid off last year for the Japan native who moved to New York at age 3, when she beat Serena Williams in the tense and turbulent final for her first major title. The aftermath of the match was a battle of emotions for Osaka, the thrill of victory mixed with sadness over watching Williams’ meltdown after chair umpire Carlos Ramos had given her a warning for receiving coaching during the match. Osaka, the No 1 seed for the tournament, has put that night behind her. She declined to discuss her relationship with Williams, who subsequently apologised to Osaka. Besides, she’s had plenty of tougher times in tennis in the year since. It certainly didn’t start that way, as she backed up the US Open title by winning the next major at the Australian Open, and eventually climbed to No 1 in the WTA rankings. But the 21-year-old lost in the third round at the French Open and was knocked out in the first round at Wimbledon, then took about a month off before starting her hardcourt season in Toronto. [caption id=“attachment_7232741” align=“alignnone” width=“825”]  Naomi Osaka, of Japan, waits for a serve from Sofia Kenin, of the United States, during the Cincinnati Masters. AP[/caption] Before ending that break, Osaka wrote a lengthy social media post in which she said she’d had some of the worst months of her life and probably hadn’t had fun playing tennis since Australia. Things have since changed, she said. “I took, like, a break sort of and kind of relaxed my mind and realized that you have to have fun doing what you love,” Osaka said. “For me, I love tennis. Sometimes I feel like I don’t, but I wake up every morning and if I don’t play, I feel like I kind of have done nothing during the day.” She went on to reach the quarter-finals in both events since, but had to stop playing in the third set of her match against Sofia Kenin in the Western & Southern Open because of discomfort in her left knee. She wouldn’t specify the nature of the injury, but said she’s able to play more lately and is healing well. And like the knee pain, the frustrations with tennis will eventually lessen as well. “I’m sure it’s going to be OK. I think time will help her to get back to normal,” said fellow Japanese star Kei Nishikori, a friend and the 2014 US Open runner-up. “I think it’s normal to have that feeling. Of course, she suddenly gets No 1, winning two Grand Slams, be No 1, like straightaway. She’s still young.” She can rely on her comfort in New York and her confidence in its courts, unlike some players. Wimbledon champion Simona Halep has been knocked out in the first round the last two years and has acknowledged that the bright lights and the big city aren’t exactly her scene. She’s working on it, going out to restaurants in the city and spending time in Central Park, in hopes that the noise in the arena won’t be so jarring once she takes the court. “I try to adjust myself as much as possible to this atmosphere. It’s loud and it’s different. Many people around,” Halep said. “I like it, but being a spectator. Being a player, it’s a little bit tougher for me, but year by year I’m getting better. So I have to work to improve more.” Osaka doesn’t have to worry about that, having lived in the city for around five years when she was younger. She made it to the third round in 2016 and 2017 before her breakthrough last September, and that has her thinking the next few weeks will be better than her previous few months. “I’m not sure if it’s because the last couple of months have been kind of turbulent, but definitely I feel really comfortable and I know that, despite everything, I play well here every year,” Osaka said. “So I’m not too worried about that.” With inputs from AP.