👋 Welcome back to The Daily Theory, our morning rundown to help you stay on top of your favorite sport. I’m Allen McDuffee, your guide to all things tennis.

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Let’s tennis!

Three Points

🎾 New coach, who dis: Coco Gauff has split with Matt Daly, the technical expert she brought in on the heels of last year’s U.S. Open to solve the ongoing problems of her serve and forehand. A year later, those issues remain unresolved (perhaps even worse in some respects), so Gauff has turned to new expertise. Gavin MacMillan, the biomechanics specialist who most notably turned Aryna Sabalenka’s serving problems around, has joined the team. MacMillan was on the court with Gauff for her Wednesday practice session on Arthur Ashe Stadium and then again out in the rain to work on her serve.

🎾 Still champs: When the new criteria for selecting mixed doubles teams to compete at the U.S. Open were revealed, defending champs Sara Errani and Andrea Vavassori weren’t sure if they would be allowed in. They were given a wild card, and now, after two days of abbreviated matches, they are U.S. Open mixed doubles champs again, defeating Iga Swiatek and Casper Ruud 6-3, 5-7, 10-6 in the final.

  • The money: Last year, when they spent a week playing full sets, they split the $200,000 check. This year, in two days, they earned $1 million.
  • What she said: “I think this one is also for the doubles players that couldn’t play this tournament,” Errani said afterwards.

🎾 Follow-up: In yesterday’s edition of The Daily Theory, I called out Emma Navarro’s match against Alycia Parks because, well, it’s been a rough stretch for Navarro. She pulled out of the U.S. Open mixed doubles to get more matches as a last-minute entry in Monterrey before the women’s singles event began.

  • Update: She lost her first match against Parks, hitting just six winners to her 24 unforced errors. That was accompanied by two aces and 10 double faults. From the beginning, Navarro was on defense and rarely converted it to offense. There seemed to be little on her ball, putting everything in the Parks strike zone.
  • Next: Navarro enters the U.S. Open with semifinal points to defend. Another early exit would mean a significant rankings slide.