Confident Osaka 'at ease' after storming into semis

World number three Naomi Osaka warned Tuesday that she's feeling confident and "at ease" after storming past Hsieh Su-wei in straight sets to book an Australian Open semi-final against Serena Williams.

The Japanese three-time Grand Slam champion overcame the Taiwanese world number 71's unorthodox style 6-2, 6-2 in an all-Asian quarter-final at a crowd-less Rod Laver Arena.

Osaka hit 24 winners in a dominant display lasting just 66 minutes against her 35-year-old opponent, who made history by becoming the oldest woman in the Open era to debut in the quarter-finals of a Slam.

After being thrown off her rhythm early by the canny Su-wei, a focused Osaka took control and then cruised to victory in stark contrast to her fourth-round match where she needed to save two match points in a tense battle against last year's runner-up in Australia, Garbine Muguruza.

"I think my confidence was raised after I played Muguruza the other day just because she's such a quality opponent, and my back was against the wall," Osaka said about coming back from 3-5 and 15-40 on her serve in the third set.

"I'm at ease with how my game is right now.

"I felt like today I told myself just to be really intense from the beginning.

"I felt like I knew what to expect and that I couldn't afford to be lazy with my footwork or anything. I didn't want to play three sets today."

Osaka, 23, will play 23-time Grand Slam winner Williams for a place in Saturday's final.

"Serena... someone that I feel really intimidated when I see her on the other side of the court," said Osaka, who beat Williams in a tempestuous 2018 US Open final.

Osaka has gone on to win the title each time she has reached the quarter-finals of a Slam and stayed on track for a second Australian Open title, having first won it in 2019.

The defending US Open champion, however, downplayed her prior achievements, preferring to focus on being consistent.

"The fact is if I don't reach the finals, I lose in the fourth round or the third round," said Osaka, who is playing in her 18th Grand Slam since starting in 2016.

"For me, I'm happy to be more consistent. I think I'm being more consistent since New York, so that's the ultimate goal for me."

Osaka is riding a 19-match unbeaten streak dating back 12 months, but exited Melbourne Park early last year after her title defence ended with a shock loss to American teenager Coco Gauff in the third round.