STUTTGART, Germany - World No.1 Naomi Osaka already has a proven track record of defying expectations and stepping up in big moments. So you can understand the 21-year-old's confusion when, in a season that saw her start the year in the Brisbane semifinals, win her second consecutive major at the Australian Open, and now make her first clay semifinal at the Porsche Tennis Grand Prix, she hears that, somehow, she's struggling.

"I don’t understand why people are saying I’m having a bad season if I won Australian Open right?" Osaka said after coming back from 1-5 down in the third set to defeat Donna Vekic in the quarterfinals of the Porsche Tennis Grand Prix. 

"Sometimes I hear people say, Naomi is kind of struggling there and I’m like yo...."

"Last year, I didn’t win Australian Open. Sure, I didn’t win Indian Wells, but I still thought I did pretty good there and in Miami, and then I’m here now. 

"So, sometimes I hear people say, Naomi is kind of struggling there, and I’m like yo...."

Aside from her opening round loss in Dubai, which was her first tournament since reaching No.1 and first tournament after her surprise split with coach Sascha Bajin, Osaka went on to make the Round of 16 at Indian Wells, where she lost to a streaking Belinda Bencic, and the third round of Miami, where she lost in three sets to the always difficult Hsieh Su-Wei. 

"I would be lying if I said it wasn’t bothering me," Osaka said of the criticism. "I tend to internalize everything, so it just builds up. I think you could tell so because I started getting really antsy on court compared to before. If I would make a mistake, I would react upon it. I feel that people that were really watching could tell. 

"I felt I wasn’t really enjoying myself. Like for me, when I play my best it’s when I have fun playing tennis and waking up every day with a new challenge. But during those few weeks, I felt like I was waking up wanting to win. I don’t think that’s a really good combo."

After a focused training block after Miami to prepare for clay, Osaka came into her first clay event of the season with an eye to check off more career milestones. Her opening round win over Hsieh was her first main draw win in Stuttgart and secured her the No.1 ranking leaving Stuttgart. She followed it up with a gritty comeback against Vekic to secure her first career clay semifinal. Her two wins over No.25 Hsieh and No.24 Vekic are the two best clay wins of her career. Prior top Stuttgart, the highest-ranked opponent she beat on the surface was No.32 Zhang Shuai at 2017 Charleston.

"It means a lot I think, especially since it’s clay," Osaka said of her Stuttgart run. Then, with a huge grin and heavy does of sarcasm: "Saving my season before it starts. I don’t know, I’ve been struggling up here."

"I spent a really long time after Miami just training on clay, trying to get comfortable with it. And I’m really happy that that paid off. I think every day I’m improving which is really good to see. So, hopefully by the time French comes I’m a decent clay court player."