Four-time grand slam champion Naomi Osaka has announced she is pregnant and is not expecting to play tennis again until next year.

The 25-year-old has not been in action since September and withdrew from the upcoming Australian Open on Sunday, but no reason was given for her prolonged absence.

However, Osaka revealed on her personal social media accounts on Wednesday that she is expecting her first child and will take a year out.

"Can't wait to get back on the court, but here's a little life update for 2023," she wrote alongside an image of an ultrasound.

"The past few years have been interesting to say the least, but I find that it's the most challenging times in life that may be the most fun.

"These few months away from the sport have really given me a new love and appreciation for the game I've dedicated my life to.

"I realise that life is so short and I don't take any moments for granted, every day is a new blessing and adventure.

"I know that I have so much to look forward to in the future, one thing I'm looking forward to is for my kid to watch one of my matches and tell someone, 'that's my mom,' haha.

"2023 will be a year that'll be full of lessons for me, and I hope I'll see you guys at the start of the next one 'cause I'll be at Aus 2024. Love you all infinitely."

The Japanese former world number one won the Australian Open in 2019 and 2021, while also winning the US Open in 2018 and 2020.

Osaka is currently ranked 42nd in the world and has been replaced by Dayana Yastremska in the main draw for the opening grand slam of the year.

"I don't think there's a perfectly correct path to take in life," Osaka added in her post. "But I always felt if you move forward with good intentions you'll find your way eventually."