Serena Williams' quest for a 24th Grand Slam title remains intact. The No.10 seed handled Simona Halep with relative ease, winning 6-3, 6-3 in the Australian Open quarterfinals.

Williams hit 24 winners over the course of her 1-hour, 21-minute victory, leading to her 40th Grand Slam semifinal overall and an Open era best ninth in Melbourne (joint with Martina Navratilova).

The last time Williams made the last four at the Australian Open was in 2017 - en route to lifting her most recent major trophy while eight weeks pregnant with daughter Olympia. It also extends Williams' winning streak against Top 3 opposition at Grand Slams to 12, dating back to her loss to Justine Henin at the 2007 US Open.

The win reasserted Williams' dominance over he second-seeded Halep after falling 6-2, 6-2 in their last meeting, a one-sided Wimbledon 2019 final. Williams pulled ahead 10-2 in the overall head-to-head, including a perfect 7-0 on outdoor hard courts. The manner in which she gained revenge was emphatic and focused.

"I feel like I needed to have a good performance today, especially after my last match against her," Williams said. "So it was really important to try to play well today. ... I knew I couldn't play worse [than last time]. So that was a good thing."

At times, Williams' quality was breathtaking. Quick to crack the ball down the line and able to conjure the sharpest of angles for winners, her commitment to first-strike tennis was lethal. But Williams, 39, would win the key points with equally brilliant defense. 

Serena Williams stretches for a forehand during her quarterfinal win over Simona Halep.

Tennis Australia/Natasha Morello

In the first set, she came out on top of a battle of angles to bring up her first break point in Halep's first service game. In the second, having pulled back from 1-3 to 3-3 and searching to underline the momentum shift, Williams came out on top of a 20-stroke rally - the kind of extended exchange in which Halep usually flourishes - to bring up her sixth break point. Williams converted after another scrambling rally.  She won eight of the final 10 points.

"It's definitely been a minute," Williams said after being asked when she last felt longer rallies belonged to her. "It's been a long minute. I think the summer of 1926 was the last time I felt that. But I'm good at rallying and I have to embrace the things I'm good at.

"The summer of 1926 was the last time I felt that."

- Serena Williams on the last time she felt long rallies belonged to her.

"Movement has always been one of my strengths, and so it's actually more natural for me to move than for me not. So it was just kind of like, Oh, that's how I used to move. I'm happy that I'm doing that again and that I put it back into my game. I think I was more focused on other things and not focused on something that is actually a strength of mine, has always been a strength of mine, and I had to refocus on that."

Halep, who tallied nine winners to 19 unforced errors, rarely found the balance she needed between offence and defense. Williams, by contrast, was quick to regain focus after her scrappier passages of play. Her unforced errors, which totaled 33, mounted most rapidly midway through the first set as she lost her opening break and at the start of the second, but neither dip would develop into anything more worrying.

Halep credited Williams afterward while pinpointing areas she could have improved.

"My feeling after this match is that I was not that far, but also, she was stronger in the important moments," the 2018 runner-up said. "I accept she beat me, but also if I could be a little bit stronger with the serve the chance could have been a little bit bigger for me. 

"In my opinion, I had a good game tonight. I'm not that disappointed about myself. Attitude maybe a little bit negative the whole tournament, but I'm gonna work on this, and I will come back stronger, for sure, with that."

Williams, who entered the tournament as the World No.11, is assured of bouncing back to No.7 on Monday and could climb as high as No.4 with the title. Her next hurdle will be another multiple Grand Slam champion, No.3 seed Naomi Osaka, whom Williams defeated 6-2, 2-6, [10-7] last month in the Adelaide exhibition A Day At The Drive.

"I have an incredible opponent to play, so it would be nice to hopefully keep raising the level of my game," Williams said. "I'm going to have to ... I feel like she does everything well. She has a good serve, she has a great return, she's strong on both sides."

Aryna Sabalenka and Elise Mertens led three of the top four seeded teams into the Australian Open doubles semifinals.

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Favorites move on to doubles semifinals

Three of the top four seeded doubles teams booked their projected slots in the semifinals on Tuesday - but new Australian Open champions are guaranteed.

No.2 seeds Aryna Sabalenka and Elise Mertens, the 2019 US Open titlists, halted the 11-match winning streak of No.7 seeds Shuko Aoyama and Ena Shibahara 6-2, 6-0 in only 53 minutes. The Belarusian-Belgian duo faced, and saved, just one break point in the whole match. They will next face No.4 seeds Demi Schuurs and Nicole Melichar, who dominated the unseeded teenagers Coco Gauff and Caty McNally after a slow start. Schuurs and Melichar fell behind 1-4 in the first set before coming back for a 7-6(4), 6-1 victory.

The top half quarterfinals proved to be tighter affairs. No.3 seeds Barbora Krejcikova and Katerina Siniakova, the 2018 champions at both Roland Garros and Wimbledon, edged Sharon Fichman and Giuliana Olmos 7-5, 5-7, 6-2 in 2 hours and 24 minutes. The Czech team will bid for their first Grand Slam hardcourt final against the only unseeded partnership in the last four, Nina Stojanovic and Darija Jurak. Having shocked No.1 seeds Hsieh Su-Wei and Barbora Strycova in the second round, the Serbian-Croatian pair continued to back up the upset, defeating Aleksandra Krunic and Martina Trevisan 6-7(3), 6-3, 6-2 to reach their first semifinal together.