NEW YORK -- A year ago, after a jarring string of injuries, Karolina Muchova lost here quietly in the first round of the US Open. She began 2023 in New Zealand as the Hologic WTA Tour’s No.151-ranked player.

On Sunday, the No.10 seed vaulted into the quarterfinals with a 6-3, 5-7, 6-1 victory over Wang Xinyu.

US Open 2023: Draw | Order of play | Scores | 411

When she’s healthy, Muchova has proven difficult to beat. She reached the final at Roland Garros this spring, losing to World No.1 Iga Swiatek. If things work out, they could meet again in Thursday’s semifinals.

For the moment, at least, the 27-year-old from the Czech Republic is healthy, thank you, and looking like a viable threat to win this thing.

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This was a brutal back-and-forth in Louis Armstrong Stadium, featuring 15 breaks in 28 service games. Muchova finished with 32 winners and 37 unforced errors. Wang went 21 and 42.

“I’m really glad I finished it and it’s over,” Muchova said in her on-court interview. “In the third set, I came to my game, to slice it more and change the rhythm -- it was the key, actually.”

And so, in her second Round of 16 appearance, Muchova advanced to her first US Open quarterfinal. She’ll play No.30 Sorana Cirstea on Tuesday.

The Romanian booked her spot opposite Muchova with a forceful 6-3, 6-3 win over No.15 seed Belinda Bencic. Breaking the Swiss Olympic champion six times, Cirstea moved through in a scant 1 hour and 24 minutes. At 33, she is the oldest first-time US Open quarterfinalist. 

There’s something about these United States hard courts that resonates with Cirstea. This spring, she made the Indian Wells quarterfinals and Miami semifinals. Six of her seven Top 10 wins this season have come on hard court.

Consider this list of players she’s beaten this year in that setting: Aryna Sabalenka, Elena Rybakina (here in the third round), Karolina Muchova, Marketa Vondrousova, Madison Keys and Caroline Garcia -- twice.

Before Sunday, Wang Xinyu had played against three Top 10 players -- all three were at Grand Slams and all three ended in defeat. Part of a rising generation of players from China, Wang won’t turn 22 until the end of the month, but this was her 10th main draw in a major and her first appearance in the Round of 16.

Despite taking her fourth Top 10 loss, her best season ever in singles and doubles continues to trend in the right direction.

Maria Sharapova, for one, saw Wang coming. Four years ago in Shenzhen, the 17-year-old Wang took the first set from her before retiring with cramps.

“You played unbelievable," Sharapova told her afterward. “If you play like that, you’re going to be No.1. I promise.”

If Wang was nervous playing for the chance to reach her first major quarterfinal, she didn’t show it. She started the match with an emphatic ace and won her first service game at love.

Then the breaks started coming.

With Wang serving at 1-all, Muchova sent a running forehand for a crosscourt winner and secured a break. Wang returned the favor, converting her second break opportunity when Muchovam buried a backhand into the net. Muchova completed the trilogy, breaking Wang a second time to take a 3-2 lead.

With a backhand winner, Muchova consolidated the break to go up 4-2. And then, with her third break point of the set, scored her third break. A fourth, achieved when she ran down a too-fat drop shot, gave her the set in 39 minutes.

Wang weathered a 12-minute game to open the second set, with some aggressive returning that eventually broke Muchova. It was the first of five consecutive breaks of serve before Wang held for a 4-2 lead. Four games later, it was 5-all.

A double fault essentially cost Muchova a chance to go up 6-5 and Wang served the set out -- after missing on five set points -- converting her sixth.

In the decisive set, Muchova broke Wang again in the fourth game to take a 3-1 lead that would ultimately not be challenged.