MELBOURNE, Australia (AP) — The Latest on Monday at the Australian Open (all times local):

2 a.m.

Record-chasing Novak Djokovic is feeling sore and tired following his late-finishing win over Daniil Medvedev, but thinks he will be OK for his Australian Open quarterfinal match against Kei Nishikori.

“I didn’t feel so great, you know, in the last 20 minutes of the match or so,” Djokovic, aiming for a record seventh men’s title in Australia, said after overcoming a couple of tumbles and a series of energy-sapping baseline exchanges in the 6-4, 6-7 (5), 6-2, 6-3 win.

Immediately after the match, he said in a TV interview that he had never felt fresher.

At a later news conference, he was more circumspect about his preparation for Wednesday’s quarterfinals.

“It was not the fall. It was not particularly the fall. It was just, you know, a little bit of fatigue, a little bit of back,” he said. “Nothing major. But there are a couple of things that have surfaced, so to say, you know, after a match like this.

“We’ll see tomorrow how the body reacts, but I’m confident I can recover and I can be ready for next one.”

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12:45 a.m.

Top-seeded Novak Djokovic overcame a couple of tumbles to the court and a series of energy-sapping baseline exchanges — one point lasted 42 strokes! — to get back to the Australian Open quarterfinals for the first time since 2016 by beating No. 15 Daniil Medvedev 6-4, 6-7 (5), 6-2, 6-3.

Djokovic has won six of his 14 Grand Slam titles at Melbourne Park and is into his 10th quarterfinal at the hard-court tournament.

But he exited in the fourth round last year and the second round in 2017.

After edging Medvedev in a 3-hour, 15-minute struggle, Djokovic joked during an on-court interview: “Since I guess my next opponent is watching, I’m feeling fantastic. I’ve never felt fresher in my life.”

His next opponent is No. 8 Kei Nishikori, whose own fourth-rounder was even more grueling, going to a fifth-set tiebreaker and lasting 5 hours, 5 minutes.

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11:30 p.m.

Kei Nishikori reached the Australian Open quarterfinals after clinching a fifth-set tiebreaker that had No. 23-seeded Pablo Carreno Busta screaming in anger as he left Margaret Court Arena.

Nishikori rallied after dropping the first two sets and had a chance to serve out at 5-4 in the fifth but was broken. Nishikori, who eventually won 6-7 (8), 4-6, 7-6 (4), 6-4, 7-6 (8), was trailing 8-5 in the tiebreaker when a contentious call changed the momentum and prompted the angry response from Carreno Busta.

Carreno Busta’s shot clipped the net, and Nishikori reset to hit a backhand down the line after the ball landed near the doubles alley.

A line judge called it out as Nishikori hit the ball down the line, and Carreno Busta was nowhere close to playing it. He challenged the decision, and Hawk-Eye showed the ball hitting the line, but the point remained with Nishikori.

After arguing with umpire Thomas Sweeney, Carreno Busta lost the next three points and Nishikori sealed the match with an ace. After shaking hands with Nishikori, Carreno Busta threw his bag into the court before collecting it and yelling at the chair umpire as he left the arena.

After spending 5 hours, 5 minutes on court in the fourth round, Nishikori will next play either six-time Australian Open champion Novak Djokovic or Daniil Medvedev.

It was the second time in four rounds Nishikori has had to come back after losing the first two sets.

It was also the second time Nishikori has had to win a fifth-set, first-to-10 super tiebreaker, which was introduced at the Australian Open for the first time this year.

Nishikori withstood 59 aces from 39-year-old Ivo Karlovic in his second-round match before winning it in fifth-set tiebreaker.

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10:30 p.m.

Simona Halep still has something at stake at the Australian Open despite a fourth-round exit to Serena Williams. So she’ll keep watching closely.

By the time the tournament concludes, Halep will have held the No. 1 ranking for 64 weeks.

Halep, the French Open champion and runner-up in Australia last year, hasn’t given up hope she’ll retain it.

“Well, there is another chance after this tournament to go back to No. 1 if I lose it,” Halep said. “So the main goal is just to play as good as I can every match, to win every match I play, so the ranking doesn’t really matter.

“End of the year is more important, the ranking, so I will not stress myself about this. I just go home, I will rest, and I will watch tennis. I am also curious who is going to win.”

Williams, who is chasing her eighth Australian Open title and record-tying 24th Grand Slam singles title overall, is not among the four women who can overhaul Halep when the next rankings are released.

U.S. Open champion Naomi Osaka, seeded fourth, and two-time Wimbledon winner Petra Kvitova have the chance to go No. 1 if they reach the semifinals. WTA Finals champion Elina Svitolina, seeded sixth, and seventh-seeded Karolina Pliskova need to reach the final to have any chance.

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9:05 p.m.

Serena Williams faced her first real test at this year’s Australian Open and emerged with a 6-1, 4-6, 6-4 victory over No. 1-ranked Simona Halep to reach the quarterfinals.

It was a back-and-forth match filled with momentum swings and terrific play by both.

Williams gained control for good after saving three break points in a monumental game to hold for 3-all in the third set. She then broke for a 4-3 lead and finally was on her way.

The 37-year-old American is trying to win an eighth championship at Melbourne Park and record-tying 24th Grand Slam title overall.

Williams next meets 2016 U.S. Open runner-up Karolina Pliskova.

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8:35 p.m.

Lucas Pouille has beaten No. 11-seeded Borna Coric 6-7 (4), 6-4, 7-5, 7-6 (2) to move into an Australian Open quarterfinal against Milos Raonic.

He hadn’t won a main draw singles match in five previous trips to Melbourne Park, but he has quarterfinals experience at other majors including Wimbledon and the U.S. Open.

Pouille, who has a 0-3 record against Raonic, is being coached by Amelie Mauresmo, the 2006 Australian Open women’s champion.

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8:20 p.m.

Top-ranked Simona Halep has taken 23-time major winner Serena Williams to a third set in their fourth-round match at the Australian Open.

Williams won the first set 6-1 in 20 minutes before Halep rallied to win the second 6-4. That ended Williams’ 21-set winning streak at the Australian Open.

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5:50 p.m.

Naomi Osaka recently took up her big sister’s suggestion to wear a wig and sunglasses to conceal her identity as she walked around in Japan.

The 21-year-old Osaka has become a big star in Japan since beating Serena Williams in last year’s U.S. Open final.

“I wasn’t really walking around (but) when I did, I went at night and had a wig on,” she said, smiling. “I wanted to try to do that. For me it was fun.”

She got the wig from her sister and tried it for a joke, but doesn’t feel like it’s necessary.

“I personally think she was making it a bigger deal than it had to be,” Osaka said. “Honestly, I feel like people don’t look at other people when they’re walking around.”

Her mother is Japanese and her father is from Haiti. She was born in Japan and lived there as a child before moving to the United States.

“I get that I’m tan and I would stand out a little bit in Japan,” Osaka said. “I think the only way people would really care is if I’m wearing some sort of athletic (gear), like, if I was walking around with my tennis racket.

“You know, other than that, I don’t think people really care too much.”

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5:30 p.m.

Karolina Pliskova continued her successful start to 2019 to advance to the Australian Open quarterfinals for the third consecutive year.

Pliskova beat former No.1 Garbine Muguruza 6-3, 6-1 in a lopsided fourth-round match.

It was the ninth straight win for Pliskova, who started the new year by winning the singles title at the Brisbane International before heading to Melbourne Park.

“I’m feeling great. I always feel good energy here,” the 2016 U.S. Open finalist said. “I feel like these conditions can be good for me.”

Pliskova made only three unforced errors during the 60-minute match in which she dominated Muguruza in their baseline duels.

She will next play either seven-time Australian Open champion Serena Williams or top-ranked Simona Halep. Pliskova planned to watch them on TV, saying: “For sure it’s going to be the match of the tournament so far.”

Muguruzu, who had the latest-starting match in Australian Open history when she went on court at 12:30 a.m. against Johanna Konta in the second round, had 20 unforced errors and dropped serve five times against Pliskova.

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4:35 p.m.

Milos Raonic has beaten racket-smashing No. 4-seeded Alexander Zverev 6-1, 6-1, 7-6 (5) on his fourth match point to reach the Australian Open quarterfinals for the fourth time.

The big-serving Canadian had his serve broken in the opening game but responded by winning the next eight games to go up a break in the second set. After falling behind 4-1 in the second, Zverev had just about enough.

The 21-year-old German sat down in his courtside chair and destroyed his racket by whacking it against the ground eight times — and then tossing it aside.

He was warned for racket abuse after the display and, after dropping the set two games later, he left the court and went to the locker room.

When he returned, he only dropped one point on his serve until the eighth game, but suddenly things went haywire again when he faced two match points. Zverev composed himself to save those two break points and led in the tiebreaker until Raonic went on a roll.

From 3-1 down in the tiebreaker, Raonic rallied to get to 6-4 and missed one more match point before finally converting.

The 2016 Wimbledon runner-up will face either No. 11 Borna Coric or No. 28 Lucas Pouille in the quarterfinals.

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3:30 p.m.

Alexander Zverev did a number on his racket.

Upset about how badly things were going in his match, Zverev sat down in his sideline chair and destroyed his racket by whacking it against the ground eight times — and then tossing it aside.

He was warned for racket abuse after the display, which came with the Australian Open’s No. 4 seed trailing 6-1, 4-1 against Milos Raonic.

Soon enough, Zverev lost the second set, too, also by a 6-1 score.

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2:05 p.m.

U.S. Open champion Naomi Osaka is into her second Grand Slam quarterfinal after another comeback win at the Australian Open, this time over Anastasija Sevastova.

Osaka had to work for nearly two hours on Rod Laver Arena to subdue the gritty Sevastova 4-6, 6-3, 6-4 in a fourth-round match studded by service breaks. She’ll next play sixth-seeded Elina Svitolina, who had a 6-2, 1-6, 6-1 win over 2017 U.S. Open finalist Madison Keys.

Osaka won a tight three-setter when she met Sevastova at the Brisbane International in the first week of the season.

Sevastova grabbed the lead in the opening set on Monday, and clinched it with a deft drop shot that forced Osaka to fly a forehand over the baseline.

Osaka had to stave off two break points in the third game of the second to edge ahead.

The fourth-seeded Osaka grew in confidence from the narrow escape and lifted her tempo and shot-making consistency, grabbing the crucial service break in the sixth game.

Serving to level the match, Osaka fended off a break-back point with a brilliant forehand volley after a long, tense baseline rally. Two points later, the match was heading into the deciding set.

Osaka broke serve to open third set to maintain the momentum.

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12:50 p.m.

Sixth-seeded Elina Svitolina has advanced to the Australian Open quarterfinals with a momentum-swinging 6-2, 1-6, 6-1 win over 2017 U.S. Open finalist Madison Keys.

The WTA Finals winner fended off five breakpoints in a pivotal third game in the third set that went to deuce 11 times and lasted more than 15 minutes. She broke Keys’ serve at the first opportunity in the next game and finished off the match quickly.

It ended a comeback by Keys, who didn’t quite find her range with her ground strokes and 34 unforced errors, including some very nears misses on big points.

Both players reached the quarterfinals here last year, but Keys had more success at the majors in 2018 when she progressed to the semifinals at the French and U.S. Opens.

“I was happy I could handle the pressure at 1-1 in the third set,” Svitolina said. “It was very hard because the sun was just burning my eyes when I was tossing the ball. Very happy I could win that game.”

Svitolina will next play either U.S. Open champion Naomi Osaka or No. 13 Anastasija Sevastova.

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11 a.m.

Madison Keys has opened play at Rod Laver Arena against sixth-seeded Elina Svitolina on Day 8 at the Australian Open.

There are spots in the quarterfinals on the line for the winners of Monday’s matches.

The 17th-seeded Keys has reached the semifinals or better at three of the last five Grand Slam tournaments. She has won both her previous matches against Svitolina including a quarterfinal victory at the 2017 U.S. Open on her way to the final.

The winner will advance to quarterfinal match against either U.S. Open champion Naomi Osaka or No. 13 Anastasija Sevastova.

In the night matches later Monday, Serena Williams continues her bid for an eighth Australian and Open-era record 24th singles major when she takes on No. 1-ranked Simona Halep, and six-time men’s winner Novak Djokovic is against Daniil Medvedev.

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