Tennis legend Martina Navratilova has criticised Naomi Osaka for being out of shape following her straight sets loss at the Australian Open to Caroline Garcia on Monday night.

The Japanese star has won the title twice at Melbourne Park, in 2019 and 2021, with her previous worst result a second round elimination back in 2017.

But French 16th seed Garcia handed the 26-year-old a 6-4 7-6 (7-2) defeat in their opening clash on Rod Laver Arena.

Navratilova, who is widely considered among the greatest tennis players of all time, said Osaka needs to be fit to win major tournaments again.

'Tennis-wise, it was maybe a B-plus performance. But overall a C, because she couldn't get to the ball. She's not in shape,' she said in an interview with the Tennis Channel.

'I'm surprised she played this tournament without clearly being in the tip-top shape she needs to be in.

'She was stretched out way too much and she didn't have a break point. That tells you all you need to know about that match.'

The one thing the tennis great said she wanted to see more of on the court from Osaka was better fitness. 

'Most of all, put in the yards on the court and off the court because the girls hit the ball too hard and you have to be quick off the mark to get to the ball to hit your shot,' she said. 

Navratilova also acknowledged that Osaka had recently given birth, but stated that 'Svitolina (Elina Svitolina) did too and she looked a lot better'.

The Australian Open was Osaka's first since the US Open in 2022 after taking time off to give birth to her daughter 6 months ago.

Fans were divided about Navratilova's comments and took to social media to comment.

'Svitolina had her baby in 2022. Naomi Osaka had her baby in July 2023 which was just 6 months ago and Svitolina had already been back on tour for 3 months by that time,' wrote one.

'Message was poorly delivered, has some truth to it though. I would have not said “out of shape” though,' replied another.

'Martina gave an accurate assessment and was totally spot on. She does know what she’s talking about believe it or not, having won 167 singles titles, 177 doubles titles,' said another.

Four-time grand slam champion Osaka said she felt a bit 'hesitant' at times which she put down to her time out of the game.

'Coming here and playing three tough matches I feel positive that I'm at least able to challenge [the top players],' Osaka said after the match.

'But the competitor in me is really frustrated that I'm not winning these matches of course.

'I wouldn't say this comeback is how I thought [it would go] because I'm delusional enough to think I could have won the tournament and I think my delusion is what allows me to win tournaments.'