Composure carries Coco through

US Open champion Coco Gauff came through a huge test at the hands of Ukrainian world No 37 Marta Kostyuk on Tuesday, winning 7-6 (6), 6-7 (3), 6-2 to reach the semifinals of the Australian Open for the first time.

The fourth-seeded American rarely plays as badly and still progress, but prevailed after more than three hours at a blistering hot Rod Laver Arena to "win ugly", fulfilling her coach Brad Gilbert's famous maxim.

"I'm really proud of the fight I showed today, Marta's a tough opponent, every time we play it's a tough match," she said.

"Yeah, I really fought and left it all out on the court today."

Gauff, playing her final Grand Slam as a teenager, swept into the last eight on a nine-match winning streak. However, Kostyuk got right in the American's face from the off and stormed to a 5-1 lead, serving twice for the opening set as well holding a set point on Gauff's serve.

The 19-year-old American knew she was up against it and, problem-solving on her feet, battled her way back into the contest by rattling off five successive games to serve for the set herself.

"I was just trying to get one more game in the first set and make it more competitive, then one game turned into another and I was able to win that set," Gauff added.

Kostyuk looked with increasing frequency at her coach as her confidence began to wane, but she earned three break points off Gauff's forehand and forced the tiebreak when the American double-faulted.

The Ukrainian was revived by treatment to blisters on her feet before the tiebreak, but blew her second set point, allowing Gauff to come racing into the net to go a set up.

The players traded breaks throughout a second set featuring some lengthy rallies, but it was Gauff who was able to edge ahead and serve for the match at 5-3.

Again, though, a combination of Gauff's frail second serve and Kostyuk's ability to conjure up winners－she fired 39 throughout the contest－allowed the Ukrainian to get back on serve and then level up the match at one set apiece.

As Kostyuk tired in the third set, Gauff found the fix by ramping up the pace of her first serve and backhand, but was broken when serving for the match for the second time.

She finally got over the line at the third time of asking, heading into the semifinals as she looks to back up her first major success in New York last year. She will face off against either Aryna Sabalenka－a rematch of last year's Flushing Meadows final－or Czech ninth seed Barbora Krejcikova.

Zhang into doubles semis

China's Zhang Zhizhen made another piece of Chinese tennis history on Tuesday when, alongside Tomas Machac of the Czech Republic, the pair produced a masterclass to reach the men's doubles semifinals at the Australian Open.

The unseeded pairing of Zhang and Machac overwhelmed Ariel Behar and Adam Pavlasek 6-3, 6-1 in a one-sided quarterfinal that lasted just one hour.

"It was an incredible match. Today we played really well, especially with our returns," Zhang said.

Zhang, who is ranked 625th in doubles, entered the match with confidence after combining with Machac to produce a considerable third-round upset over doubles specialists Rajeev Ram and Joe Salisbury, who had won the last three US Open doubles titles and also triumphed at Melbourne Park in 2020.

But the Chinese-Czech pairing were wary against fellow giant killers Behar and Pavlasek, who had knocked out fifth seeds Santiago Gonzalez and Neal Skupski in the third round.

Zhang and Machac soon gained control through relentless returns of serves, as the new pairing raced through the second set to reach the final four.

They will now face either second seeds Matthew Ebden and Rohan Bopanna, or sixth seeds Maximo Gonzalez and Andres Molteni.

It has been an impressive bounce back for Zhang, China's highest-ranked men's singles player, who fell in the second round to 21st seed Ugo Humbert in four sets.

"We worked so well because my partner was doing so good. He did a very good job on his side and also covered my side. It's been an amazing two weeks, but we're still not finished yet. We are looking forward to the next round," the 27-year-old Chinese said at a post-match news conference.

Machac hailed Zheng's serving and noted that they had "a great combination" on court.

"We are looking for more and we aren't satisfied with anything now. It's a great result for us for sure, but the title is the title. So, we'll do our best to get through the semis to the final. Let's see how far we can go, but we will do everything possible to achieve something incredible," said Machac.

Agencies - Xinhua