Naomi Osaka's birthday was far from ideal as she spent some time at the hospital after sustaining a thigh injury during the ongoing Japan Open.The Japanese took a medical timeout to treat her left leg in the deciding set of her last-16 clash with defending champion Suzan Lamens on Wednesday. She ultimately won the match 7-6(8), 3-6, 6-2.Osaka turned 28 on Thursday, but celebrations were marred by a visit to the hospital, from where she uploaded a bunch of pictures, including a selfie and one of her birthday cake."Happy birthday 😂?" Osaka wrote. View this post on Instagram Instagram PostOsaka also penned a humorous note on Threads that read:"Going to the hospital on your birthday is a whole new level of hilarious."The 28-year-old will lock horns with Jaqueline Cristian in the quarterfinal on Friday.Naomi Osaka expressed feelings about post-pregnancy struggles, opening up about her progressNaomi Osaka gave birth to her daughter, Shai, on July 7, 2023. After her pregnancy, she faced various struggles, including hair loss. In a recent TikTok video titled 'For My Hair Girlies Only,' she opened up about her struggles and how she has addressed the issue.“This is a very weird video. I've been really struggling with my hair for like the past two years. Like, during pregnancy and after pregnancy I lost my edges and stuff," said Naomi Osaka. She added:"They’re back now. Well, kind of. Kind of! Don’t look too closely. I also dyed my hair a lot, so I had to cut it off, blah, blah, blah. But I think it’s back now.”Additionally, Osaka mentioned that during her period of hair loss, she would often tie her hair into a ponytail.“Anyway, I’ve been wearing a ponytail, as you can tell, because I didn’t know how to wear my hair. And then I watched one TikTok yesterday—don’t look too close, again—but I think we’re back! Hey!”Ahead of the Japan Open, Naomi Osaka competed at the Wuhan Open, where she was defeated by Linda Noskova in the Round of 32.