US Open Day 1 betting guide: How to bet on the opening round of the tournament with Dimers

The stage is set in New York City as the 2025 US Open begins at Flushing Meadows on August 24. Running through September 7, the final Grand Slam of the year is more than just tennis—it’s a proving ground where legacies are forged and underdogs dream big. With Jannik Sinner and Carlos Alcaraz dominating the men’s game, and Iga Świątek and Aryna Sabalenka leading the women’s field, anticipation is at a fever pitch.

Add in Dimers’ biggest betting offering ever—expanded markets, new bet types, and broader sportsbook coverage—and there’s never been a better time to bet on the US Open.

Flushing Meadows will once again be the battleground where the world’s best clash under the lights. Last year, Sinner claimed the men’s title with a straight-sets win over Taylor Fritz, while Sabalenka lifted the women’s crown in a hard-fought final against Jessica Pegula.

This year’s schedule stretches over two weeks, beginning with the first-round matches from August 24–26 and culminating in the women’s final on September 6 and the men’s final on September 7. Fans are already circling the possibility of another Sinner–Alcaraz showdown, as the two have split the last two Grand Slam finals and now own seven consecutive major titles between them.

Here's your guide to betting on Day 1 of the tournament.

US Open Tournament Favorites

On the men’s side, Sinner (+110) and Alcaraz (+175) are the clear frontrunners, with Novak Djokovic (+1400) lurking as a dangerous outsider. While the Dimers model has Sinner and Alcaraz leading the way, we give a slight edge to Alexander Zverev over Djokovic as the third-most likely winner of the US Open.

The women’s draw projects much tighter, led by Iga Świątek (+240), who looks resurgent on hard courts, followed closely by Aryna Sabalenka (+285), the defending champion eager to reassert herself after an up-and-down season. Coco Gauff (+700) rounds out the top three, backed by a roaring home crowd. The women's side mirrors Dimer's top 3 and you can view our full outlook for the women's draw here.

If you're looking for value among the tournament winners, check out Nick Slade's Best Bets to win the US Open.

A peek at our most likely winners for the Men at the US Open.

Opening Day’s Tightest Matches

Dimers’ predictive models point to four razor-thin contests on Day 1, where bettors should expect tense, back-and-forth play:

Adrian Mannarino (+138) vs. Tallon Griekspoor (–152)
Win Probabilities: Mannarino 46.1% | Griekspoor 53.9%

Matteo Arnaldi (+110) vs. Francisco Cerundolo (–132)
Win Probabilities: Arnaldi 45.3% | Cerundolo 54.7%

Nuria Parrizas Diaz (+110) vs. Polina Kudermetova (–125)
Win Probabilities: Parrizas Diaz 48.1% | Kudermetova 51.8%

Lulu Sun (–138) vs. Camila Osorio (+120)
Win Probabilities: Sun 54.4% | Osorio 45.6%

These matches are virtual coin flips, and sharp bettors may look to capitalize on the slim margins and should examine Dimers' predictions and value bets in each match.

Sunday's closest projected match between Nuria Parrizas Diaz and Polina Kudermetova.

Dimers’ Top Value Bets for Day 1

Dimers highlights “High Value” bets when favorable odds line up with strong probability. Three wagers stand out on opening day:

Rebeka Masarova +7.5 games vs. Aryna Sabalenka
Win Probability: 69.3% | Edge: 12.4% | Best Odds: –132 (FanDuel)

Emilio Nava vs. Taylor Fritz: Under 34.5 games
Win Probability: 63.5% | Edge: 9.0% | Best Odds: –120 (DraftKings)

Jakub Mensik vs. Nicolas Jarry: Under 40.5 games
Win Probability: 61.2% | Edge: 6.6% | Best Odds: –120 (DraftKings)

Each of these represents strong expected value, particularly Masarova’s spread, which offers the best edge and the highest probability on Day 1

To find more value bets, including some moneyline upsets and more, check out Dimers' Best Tennis Bets every day of the US Open.

Our best value and highest probability bet for the opening day of the US Open.

Betting the US Open Smartly

Opening day is all about balance—taking advantage of sharp value edges while recognizing the volatility of early rounds. Sinner and Świątek look like safe outright bets, while Dimers’ Day 1 “High Value” picks provide bettors with calculated opportunities. Keep an eye on tight matches like Arnaldi vs. Cerundolo, where early upsets could shake the draw and the odds.

With Flushing Meadows buzzing, the 2025 US Open is primed for drama, and Dimers is giving bettors every tool they need to play it smart.

Responsible Gambling

Remember to please gamble responsibly. If you sense that you're taking your luck too far, know when to call it quits and don't be afraid to seek assistance. Keep in mind that gambling is all about having a fantastic experience! If you or someone you know is grappling with gambling issues, reach out to 1-800-GAMBLER for crisis counseling and support.