The US Open mixed doubles has already been a rollercoaster. Fans were excited for its star-studded lineup and have turned out in droves. But doubles players weren’t thrilled to see that the champions of their own format were sidelined in favor of including more singles stars. And 2-time Olympic gold medalist, Katerina Siniakova was one of those voices speaking out. The former World No.1 in doubles didn’t receive a wildcard, but earlier this week, it was announced that she would team up with ATP No.1 Jannik Sinner. Then things unraveled, and the debate was reignited all over again.

During a discussion on the latest updates from New York, The Tennis Podcast hosts David Law, Catherine Whitaker, and Matt Roberts weighed in on Sinner’s withdrawal. The Italian had pulled out before their scheduled match, and instead of partnering her up with another player, Siniakova lost her chance to compete entirely. But Whitaker didn’t hold back. “Personally, I feel like the USTA have treated the rules of doubles such that, if it weren’t Katerina Siniakova, that rule might have been bendable. Like, if Swiatek had been in the position, I feel like rules might have changed or been bent,” she said.

To catch you up: on Tuesday, mixed doubles in New York was set to start with Jannik Sinner partnering Katerina Siniakova against Alexander Zverev and Belinda Bencic. But fresh off his retirement in the Cincinnati final, and still unwell, Sinner needed time to recover. He pulled out and that opened the door for Danielle Collins and Christian Harrison to step in.

Since announcing its mixed doubles pairings and wildcards, the USTA has faced heavy criticism. Siniakova has been vocal from the start, and she isn’t alone. Many top doubles players have slammed the governing body for turning what should be a Grand Slam race into something closer to an exhibition.

Placing the event during Fan Week, before the main draw, only fueled criticism. The format allows just 16 teams. Eight are wildcards, and the other eight come from singles rankings. It leaves doubles specialists out in the cold. As Siniakova told Canal+ in July, “When two world number ones in doubles [Siniakova and Arevalo at the time] don’t get into the tournament, there’s probably nothing more to say about it.” 

For the Czech star, the sting cuts deep. She and men’s World No.1 Marcelo Arevalo  had to formally apply for a wildcard to play as a pair. When the updated list of wildcards was revealed, neither she nor Arevalo were included and she went to Instagram with a pointed note: “How many more surprises are coming? 🤔😃”  The rejection of the Siniakova/Arevalo pairing came despite her remarkable resume—10 Grand Slam doubles titles, 2 Olympic golds, and, just last month, her first Grand Slam mixed doubles crown at Wimbledon 2025 with Sem Verbeek. Yet, she got her spot only because Sinner’s original partner, Emma Navarro, dropped out. And ultimately Siniakova had to sit the tournament out entirely.

The frustration has caught wider attention. The Tennis Podcast host Catherine Whitaker put it sharply: “But, you know, the USTA never wanted Katerina Siniakova in this tournament, did they? They wanted Jannik Sinner, and she was a vehicle for Jannik Sinner. So poor old Siniakova on this scrap heap—enter Christian Harrison. Like, she must be furious.”

While Harrison brings his own doubles credentials, having reached the US Open mixed doubles semifinals under the old format and claimed two ATP doubles titles this year with Evan King in Dallas and Acapulco. Still, for many, seeing Siniakova sidelined again doesn’t sit right. Even Rennae Stubbs voiced her frustration.

Renae Stubbs gives her take on the Jannik Sinner – Katerina Siniakova controversy

After Jannik Sinner’s withdrawal from the tournament, fans were quick to voice their frustration over Katerina Siniakova’s removal as well. The backlash was fierce, especially given Siniakova pulled out of Tennis in the Land, a WTA 250 in Cleveland, just to play the US Open mixed doubles. With 11 Grand Slam doubles titles and two Olympic golds to her name, it was no surprise her supporters felt she deserved better. The reaction was summed up by The Tennis Letter in an X post calling it a “Sad way to treat one of the best Doubles players in the world.”

But in came a surprising voice of support for the US Open organizers—Serena Williams’ former coach, Rennae Stubbs. Replying directly to The Tennis Letter, Stubbs didn’t sugarcoat her view. “These are the rules! Does it suck, yep! This is the same in doubles too. If the draw is made, this is just too bad. It’s not the first time, and won’t be the last time it happens. Get your rule book out.” Her blunt defense didn’t sit well with many fans. One even pushed back, demanding explanations for other substitutions in the draw.

Stubbs held firm, pointing straight to the regulations. The difference, she explained, was timing. Other pairings were switched before the draw had been finalized. Sinner, however, withdrew after it was already set. That meant no replacements were possible. “The rules are the rules! Once the draw is made, you CANNOT CHANGE PARTNERS! Before the draw is made, there can be changes in partners, but they still have to be high enough to get in. That’s THE RULES! Relax! And get educated,” Stubbs wrote in reply.

Still, even as she defended the USTA, Stubbs voiced frustration at another issue—the decision to stage a Masters 1000 final on a Monday. That debate rumbles on. Meanwhile, the mixed doubles event marches forth stands packed, with the likes of Jack Draper, Jessica Pegula, Iga Swiatek, and Casper Ruud charging into the semifinals. As for the Siniakova saga? It lingers, and only time will tell what happens next.