Two favorites, two unseeded champions: Breaking down Tuesday's US Open quarters

NEW YORK -- The two highest-seeded players in the top half of the draw -- No. 1 Aryna Sabalenka and No. 4 Jessica Pegula -- are through to Tuesday’s quarterfinals at the US Open.

They’re also (not coincidentally) the defending finalists here.

Their opponents aren’t seeded players, but they know how to win Grand Slams. The Czech Republic’s Barbora Krejcikova and Marketa Vondrousova, former Wimbledon champions both, have fought their way through injuries in recent years and are surprise arrivals in the elite eight.

Vondrousova upset No. 9 Rybakina 6-4, 5-7, 6-2 late Sunday night. Krejcikova, who defeated No. 10 Emma Navarro in the third round, saved eight match points in the fourth round against Taylor Townsend to win a three-hour-plus match.

The last time two unseeded players from the same country reached the US Open quarterfinals? Sixteen years ago, Belgians Kim Clijsters and Yanina Wickmayer did it.

We make the case for Tuesday’s quarterfinalists:

No. 1 Aryna Sabalenka vs. Marketa Vondrousova

Head-to-head: 5-4, Sabalenka, who has won four of their five previous meetings on hard courts.

Advantage, Sabalenka

The pressure’s off.

Coming into this US Open, both Iga Swiatek and Coco Gauff could have taken the No. 1 PIF WTA Ranking from Sabalenka. But by defeating Cristina Bucsa 6-1, 6-4 and advancing to the quarters, Sabalenka guaranteed herself the top spot after the tournament concludes.

“I’m enjoying being World No. 1,” Sabalenka said afterward. “I’m enjoying this pressure. I’m working really hard to be where I am. I think for me it’s important to focus on my game and on bringing, try to bring my best tennis and just to fight.

“I know I’ll have my chances, but for me, it’s a fun life if you’re really enjoying your job.”

Indeed, Sabalenka has really leaned into being No. 1, perhaps more than any other player since Serena Williams. Sabalenka is the first woman to reach the quarterfinals at all four Grand Slam events in a single season as World No. 1 since Serena in 2016.

Since 2021’s Wimbledon, when Sabalenka reached her first major quarterfinal, no woman has made as many quarters as her 14. In that time, she’s won three majors, made the finals twice and the semifinals six times.

Advantage, Vondrousova

She’s just feeling it.

You could hear it in her voice after she took out Rybakina. Two major surgeries in the past several years left her feeling vulnerable -- and grateful for her return to elite tennis.

And you could see it in the last game, when a fired-up Vondrousova fired three consecutive aces. She had 13 overall and now has 27 for the tournament -- the most of any woman left at the end of play Sunday.

She’s produced terrific victories over No. 7 Jasmine Paolini and now No. 9 Rybakina. The last time she had multiple Top 10 wins was Wimbledon 2023 -- a tournament she won for her only major.

Another nugget that suggests success: Vondrousova is the first unseeded woman to claim multiple Top 10 wins on the way to a Grand Slam quarterfinal since Garbiñe Muguruza in 2020. She went on to reach the final at the Australian Open.

Their most recent match, a few weeks ago in Cincinnati, had a 7-5, 6-1 scoreline in favor of Sabalenka. But the crafty Vondrousova created six break-point opportunities in each set.

“It’s always a tough match against her,” Sabalenka said after the match. “[Vondrousova] always pushes me to the limit. You have to stay focused, and you have to fight for every point against her.”

No. 4 Jessica Pegula vs. Barbora Krejcikova

Head-to-head: Krejcikova holds a 2-1 advantage over Pegula, winning their most recent match 6-3, 6-3 in last year’s WTA Finals in Riyadh.

Advantage, Pegula

Pegula split four matches in Montreal and Cincinnati, losing one of them to No. 386-ranked Anastasija Sevastova in three sets.

“I felt terrible coming into this tournament, honestly,” Pegula told reporters. “I had a practice Wednesday. I hit with [Aryna] Sabalenka. She killed me.

“Went and did an escape room with my friends and had, like, two drinks and was, like, ‘I need to just chill and stop getting so frustrated and overthinking all these practices.’”

In four matches here, Pegula has been transformed into a chilling opponent, dropping only 17 games, her fewest ever on the way to her seventh major quarterfinal. Those flat, deep groundstrokes have been too much.

Pegula is 31, the oldest woman left in play, but that experience has paid dividends. No one has won more games (22) on American soil this year than Pegula. Her 41 overall wins are tied for fourth behind only Sabalenka, Iga Swiatek and Rybakina. 

Pegula is an accomplished doubles player, winning seven titles, but her coaches -- Mark Knowles and Mark Merklein -- have been lobbying for her to come forward more often. Against Li, she won 12 of 15 points at net. That new dimension could swing the match.

Advantage, Krejcikova

Two years ago in Madrid, Krejcikova was asked what she thinks about when playing match points.

“Nothing,” she said. “You try to take it like it’s just a normal point.”

And that is precisely why Krejcikova has won two Grand Slam singles titles, seven more in doubles and three in mixed.

In their fourth-round match, Taylor Townsend had eight match points against Krejcikova -- and saved them all on her way to a dramatic three-hour, three-set win.

“I was just very brave, but also lucky at certain points, because we had great rallies,” she told reporters. “I was just trying to put the ball on her side, in that space, and hoping that, yeah, I’m going to save it.”

Krejcikova came in with a modest 8-6 record, trying to regain her form after a six-month sabbatical with a back injury.

She’s unseeded here but has already taken out No. 22 seed Victoria Mboko and battled past No. 10 seed Emma Navarro in a three-set, third-round brawl.

Against Taylor Townsend, she faced a partisan Louis Armstrong Stadium crowd and still found a way through. Her postmatch fist pump said it all.

After wondering if a back injury might end her career, every win now carries extra weight. And that edge makes her dangerous.