Jannik Sinner’s unexpected retirement from the Cincinnati Open finals not only cost him the ATP Masters 1000 title but also impacted him and his doubles partner at the US Open.
While excitement surged over Sinner’s last-minute partnership with Kateřina Siniaková in the revamped mixed doubles format, his withdrawal left the Czech WTA star with no option but to step back from the event as well.
So, what’s the US Open rulebook clause that brought an abrupt end to Siniakova’s mixed doubles hopes after Sinner’s exit?
The Reason Behind Kateřina Siniaková’s Forceful Mixed Doubles Exit
World No. 1 Sinner made an unexpected exit from the Cincinnati Open final on August 18, 2025, just 23 minutes into the match. Trailing 0–5 to Carlos Alcaraz, Sinner retired due to illness, saying he felt as if he could collapse and apologized to the crowd for letting them down.
Less than 24 hours later, he and his mixed-doubles partner, Siniaková, also withdrew from the newly revamped US Open mixed-doubles event. Tournament officials replaced them with an alternate team, enraging tennis fans.
– Schedule your mixed doubles tournament to take place during real tournaments
– Siniakova skips Cleveland to play in your thing
– Siniakova’s partner WD’s
– Siniakova now can’t play mixed doubles OR ClevelandWell thought out and planned by US Open!
— Owen (@kostekcanu) August 19, 2025
Sinner wasn’t in a position to compete, as he recovered from illness before the singles main draw. Siniaková, a one-time mixed doubles champion and 10-time women’s doubles champion at Grand Slams, also had to end her hopes for entry, mainly because of one major rule from the US Open rulebook.
“Players may not change partners after the doubles entry deadline. In no case shall any player change partners after the draw has been made unless the draw is remade due to the withdrawal of seeded teams,” the clause under ‘Main draw doubles entries and withdrawals’ reads.
It should be noted that the initial US Open mixed-doubles entry list featured Sinner as the top seed alongside Emma Navarro. After her withdrawal, the World No. 1 re-paired with Siniaková, making them an unseeded wildcard entry, considering the doubles star’s low singles ranking.
Who Replaced Jannik Sinner and Kateřina Siniaková at the US Open?
Sinner’s preliminary message after his Cincinnati Open retirement did not mention whether he would still contest the US Open mixed doubles, which led to questions about his fitness to compete. Soon after, tournament organizers confirmed that Americans Danielle Collins and Christian Harrison have taken his and Siniakova’s place in the draw.
The new pair contested their first match against Switzerland’s Belinda Bencic and Germany’s Alexander Zverev, winning 4-0, 5-3. In the quarterfinal, they beat compatriots Ben Shelton and Taylor Townsend 4-1, 5-4(2).
They face Italian defending champions Sara Errani and Andrea Vavassori in the semifinal on Wednesday, August 20. The winners take on either Jessica Pegula and Jack Draper or Iga Świątek and Casper Ruud in the final.
