Stuttgart - World number one Naomi Osaka said Tuesday she had "dodged a bullet" after Simona Halep, her main pursuer in the WTA rankings, pulled out of this week's tournament in Stuttgart.

Japanese rising star Osaka, 21, launches her clay season in Stuttgart this week, and her hopes of holding on to her spot at the top of the rankings were given a boost when world number two Halep withdrew with a hip injury earlier Tuesday.

"She was getting really close," said Osaka, who is less than 200 points ahead of Halep in the WTA rankings. "I feel like I dodged a bullet there."

Osaka said that winning was not everything in Stuttgart, where she last played as a qualifier in 2017.

"I don't want to overhype myself and say, 'I will win the tournament'," she insisted.

"I just want to have fun and experience the German crowd, because last time I was here, I was kind of a nobody."

She is definitely no longer a 'nobody', having won back-to-back Grand Slam titles in the United States and Australia since September.

However, she admitted finding it difficult to adjust to her newfound global fame.

"It is something that happened really quickly. In the beginning it was tough for me, because I put a lot of pressure on myself," she said.

"I feel like there is certain things, I should be doing, that I am not doing right now."

Osaka has not won a title since her Australian Open triumph in January, suffering early exits at three recent WTA tournaments.

She was reluctant to speak about her split with her German coach Sascha Bajin earlier this year. "I feel like I get in trouble for answering questions like this. There were irreconcilable differences," she said.

Osaka said she hoped to get more used to playing on clay ahead of the French Open next month.

"I feel, that on every surface of the season I do have a lot more experience than on clay."

"The bounces are different and you have to swing for the ball. For me it is a little bit difficult, because I cant hit as flat."

Osaka is expected to play her first game on Thursday, where she faces a potential clash with Taiwan's Hsieh Su-wei, who beat her in Miami last month.

Reigning Wimbledon champion Angelique Kerber, meanwhile, has recovered from illness in time to launch her clay season on home soil as she eyes a career Grand Slam in Paris this year.

Kerber has won every major except the French Open since 2016, but she has never got past the quarter-finals at Roland Garros.

"You know clay and me, you know the story," she told reporters with a smile on Monday.

"It's a tough challenge (to win all four Grand Slam tournaments), but I will not put too much pressure on my side."

"Right now, I will focus on the tournaments ahead, and then when I'm in Paris, I will think about the Paris situation."

Kerber missed out on Germany's Fed Cup play-off win over Latvia last week after she picked up an illness earlier this month, but said on Tuesday that she had returned to full strength.

Halep's absence has given the German a little more breathing space.

Instead of playing a first-round match against Donna Vekic on Wednesday, Kerber gets a bye to the second round, where she faces a potential clash with compatriot Andrea Petkovic.