A pre-U.S. Open party seemingly has tennis integrity officials calling fault.

Several of the sport’s biggest stars attended a bash fronted by Miami restauranteur and club owner Dave Grutman at the Crane Club in NYC, one sponsored by DraftKings — which caused it to be flagged to the International Tennis Integrity Agency, according to tennis insider Ben Rothenberg.

“We are aware of this event, and we are looking into the circumstances and details,” an International Tennis Integrity Agency spokesperson told Rothenberg.

Serena Williams and Coco Gauff attend David Grutman & Draft Kings hosted a US Open players dinner at Crane Club on Aug. 27 2026. BrokenRacketsCoco Gauff attends a US Open players dinner hosted by David Grutman and Draft Kings at Crane Club in New York on August 27, 2026. BrokenRackets

Grutman posted an Instagram carousel from the event, with Arnya Sabalenka, Serena Williams, Eva Lys, Mirra Andreeva and Coco Gauff posing with the host in front of a DraftKings-branded backdrop.

“Hosting @draftkings Welcome Players Party is my Favorite!!!” he captioned the post.

Paige Paul and David Grutman attend a US Open players dinner hosted by David Grutman and Draft Kings at Crane Club in New York on August 27, 2026. BrokenRackets

Grutman’s Groot Hospitality portfolio includes Miami hotspots Gekko, Casadonna, Komodo and the LIV nightclub, with tennis lifestyle brand Prince.

According to his personal website, he counts DraftKings among his partners.

Per Rothenberg, players were not paid to appear at the event, but could still be in violation of anti-corruption rules by attending the shindig due to it’s DraftKings association.

“No Covered Person shall, directly or indirectly, facilitate, encourage and/or promote Tennis Betting,” Tennis Anti-Corruption rule D.1.b reads, while rule D.1.q adds that “No Covered Person, whether personally or via another arrangement or legal entity, may endorse, be employed, sponsored and/or otherwise engaged by a Tennis Betting Operator.”

Punishment could come in the form of a private warning, though Rothenberg notes former players James Blake, Mardy Fish and Bob Bryan were all hit with five-figure fines for paid promotions for gambling companies.

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Grutman — a self-described “obsessed” tennis fan — has close ties with some of the biggest names in the sport, often hooking them up with perks when in Miami and beyond, per Rothenberg.

Aryna Sabalenka attends a US Open players dinner hosted by David Grutman and Draft Kings at Crane Club in New York on August 27, 2026. BrokenRacketsDavid Grutman, Matteo Berrettini, Taylor Fritz attend attends David Grutman & Draft Kings hosted a US Open players dinner at Crane Club in NY on August 27 2026. BrokenRackets

Other attendees included Taylor Fritz, Matteo Berrettini, Alexandra Eala, Anna Kalinskya and ESPN commentator Caroline Wozniacki.

Kalinskya told Rothenberg she “went to catch up with my friends,” but did not know the party was sponsored by DraftKings.