No.4 seed Coco Gauff of the United States breezed into the first Australian Open quarterfinal of her career with a 6-1, 6-2 victory over Poland's Magdalena Frech on Sunday.

"First Aussie quarterfinal, super happy to be in this position and be here," Gauff said after her win. "It's cool to get over that hump. Hopefully I can keep going for more."

Gauff, the reigning US Open champion, needed just 63 minutes to prevail over World No.69 Frech on Rod Laver Arena -- with Australian legend Laver himself in attendance.

The American teen will next face first-time Grand Slam quarterfinalist Marta Kostyuk of Ukraine. Kostyuk broke through to the last eight with a 6-2, 6-1 victory over qualifier Maria Timofeeva in Kia Arena on Sunday.

Fast facts: With her latest win, Gauff has extended her undefeated start to the season. The American successfully defended her Auckland title in the first week of the year and is now up to 9-0 in 2024.

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The 19-year-old Gauff is the youngest woman to reach the Australian Open quarterfinals since Agnieszka Radwanska in 2008. The last teenager to make it into the elite eight in Melbourne was Madison Keys in 2015, who was then a month shy of her 20th birthday. 

Frech was contesting a Grand Slam Round of 16 for the first time on Sunday. Earlier in the week, the Pole notched her first Top 20 win by upsetting Caroline Garcia, but she is now 0-11 against Top 10 opposition following her loss to Gauff.

Match moments: Sunday's match started with Gauff firing a forehand winner to break Frech in the opening game, and the American zoomed through the first set from there. Gauff converted three of her four break points in the opener.

Gauff continued to control proceedings in the second set, and she wrapped up the match with a backhand passing winner that fell barely inside the corner of the court.

Gauff never faced a break point all day, and her 21 winners tripled Frech's seven as she booked a spot in the quarterfinals. Gauff bettered her pair of Round of 16 showings in Melbourne, which took place in 2020 and last year.

Kostyuk next up: Gauff will meet one of the highest ranked unseeded players, World No.37 Kostyuk, in the quarterfinals. Gauff is 1-0 against Kostyuk, but she needed three sets to get that win, which also came Down Under in Adelaide two years ago.

The 21-year-old Kostyuk had taken the long way into this fortnight's Round of 16, going three sets in each of her first three matches. Kostyuk even had to save a match point in her second-round victory over No.25 seed Elise Mertens.

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But everything came together for the Ukrainian in Sunday's match, as she swept past Timofeeva in 1 hour and 16 minutes of action. Kostyuk also successfully shook off a 40-minute rain delay which came just two games into the match.

Kostyuk, who had a breakout Grand Slam debut when she made the Australian Open third round as a 15-year-old in 2018, had no issues winning in her second Round of 16 match at a major. She had previously posted a Round of 16 result at 2021 Roland Garros.

On Sunday, Kostyuk won 47 percent of her return points, converted 21 of 29 points at net, and saved all four break points she faced en route to her maiden Grand Slam quarterfinal.