2023 Australian Open: Korda, Shelton win five-set thrillers, Pegula returns to QF

"I think that really helped me, especially in the last match with Medvedev, closing out that tiebreaker. Then today as well. I think all those little moments that I've gone through, kind of learning from them, staying patient, staying positive, going through the process I think have really helped me going forward."

Korda will face No. 18 seed Karen Khachanov for a spot in the semifinals. Though Korda leads the overall head-to-head 2-1, Khachanov won the pair's only previous meeting at a Grand Slam: 10-8 in the fifth set at Wimbledon in 2021. 

Shelton's dream debut continues with quarterfinal berth; Paul through too

This time last year, University of Florida sophomore Shelton was playing No. 3 singles at the University of Texas. Now, he's a Grand Slam quarterfinalist. The fastest-rising star in men's tennis took another step in Melbourne on Monday with a 6-7(5), 6-2 ,6-7(4), 7-6(4), 6-2 fourth-round win over fellow American J.J. Wolf.

Shelton never lost serve in the 3 hour, 47-minute affair between two former NCAA stars. He hit 23 aces and 64 winners in all; after serving to stay in the match twice in the fourth set, Shelton took control of the tiebreak and cruised in the decider as Wolf began to struggle with a leg injury. 

Shelton is the first NCAA men’s singles champion to make the following year’s Australian Open quarterfinal since Arthur Ashe in 1966, and is the youngest American man to reach the last eight at a major before turning 21 since Andy Roddick 20 years ago. 

"It's been a dream so far," Shelton said on-court afterwards. "It was definitely a grueling match. There were a lot of swings throughout the match ... I really focused on, in the fifth set, just being energetic, trusting my fitness, just hustling and being courageous, and I thought I did a really good job of competing at the highest level in the fifth set.

"It's always thought playing a friend. I've known J.J. for a while, and he's a great guy ... I knew it was going to be a battle. I paced myself emotionally, and I was able to bring out some of my best tennis at the end of the match."

An American man is gauranteed to reach the semifinals. Shelton will next face Tommy Paul, who was a 6-2, 4-6, 6-2, 7-5 winner over No. 24 seed Roberto Bautista Agut. It's the first time three American men have reached the AO quarterfinals since 2000.

"It's like every person's dream when they start playing tennis to play the big matches at the Slams," Paul said. "I'm really excited to get out there on Wednesday. We know there's going to be an American in the semis, so I'm really excited about that, too."

Pegula reaches third straight AO quarterfinal, Gauff falls to Ostapenko 

There were mixed fortunes against two former Roland Garros champions for the last two American women remaining. 

While third-seeded Pegula was a 7-5, 6-2 winner against No. 20 seed Barbora Krejcikova, No. 7 seed Coco Gauff fell to No. 17 seed Jelena Ostapenko, the 2017 winner in Paris, 7-5, 6-3. 

With world No. 1 Iga Swiatek's defeat at the hands of Wimbledon champion Elena Rybakina earlier in the day on Sunday, and No. 2 seed Ons Jabeur having lost in the second round, Pegula is now the highest seed left in the tournament. , and reach the first major semifinal of her career, against two-time former champion and No. 24 seed Victoria Azarenka.

"It's an interesting feeling, I guess. I still don't really feel like that," Pegula said. "I look at the draw and there's still girls ... today, [Krejcikova] she won French Open, you have Rybakina who won Wimbledon last year, you have Vika who does really well here, Caroline [Garcia] won the [year-end] championships.

"It doesn't really feel like I'm the highest left, even though I guess that's a cool stat. It feels like there's still a long ways to go."

Pegula and Azarenka are 2-2 all-time. Pegula's wins came two years ago at the Australian Open, and last fall at the WTA 1000 event in Guadalajara, which she went on to win. 

"She loves to play here. I've played her in a couple tough matches," Pegula said. "Gone both ways. She's just a great competitor. I feel like when she's on and she's playing her game, she can just be relentless with her style. She plays very smart as well, returns very well, puts a lot of pressure on you I feel like constantly.

"I don't really feel like a favorite because I'm going against people that have had more success than me. I guess currently seeding-wise I'm the favorite. ... I guess I feel more confident, I feel more experience being in this position. I will still have a tough match next match no matter what. But I think I definitely feel maybe a little bit more settled than I have in the past in those tournaments."

Americans could have as many as four quarterfinalists in the men's and women's singles draws. Ben Shelton will play J.J. Wolf in an all-American Round 4 match on Monday, while Tommy Paul faces Roberto Bautista Agut.