Sabalenka Leads the US Open Field, but Rybakina Is Closing Fast

Aryna Sabalenka enters the US Open as the favorite to claim the women's singles title, but the margin of confidence has narrowed overnight in a way that demands attention. What had been a comfortable lead has tightened into a lean: the money now gives Sabalenka a 55% chance of lifting the trophy at Flushing Meadows, down from a peak of 60% eleven days ago, while Elena Rybakina has climbed to 46% — the two women now accounting for nearly all of the probability in the field.

The shift matters because of how it happened and where. Kalshi, the significantly deeper market by a wide margin in recent trading, prices Rybakina at 46%, while Polymarket sits a few points lower at 42%. That spread between venues is worth noting: when the market carrying roughly 34 times the daily volume leans more generously toward the challenger, it is the number that commands more weight. The deeper money, in other words, sees this as closer to a true coin flip between two players than the headline favorite's 55% suggests.

The underlying logic is not hard to reconstruct. Rybakina's game — flat, heavy ball-striking off the ground and a serve that neutralizes pressure — translates exceptionally well to the hard courts of New York. Sabalenka, the defending champion and top seed, has the power and the experience at this venue, and her probability never collapsed even when it fell to a low of 21% roughly four weeks ago amid early uncertainty about her form and draw. That she has since recovered to 55% reflects genuine confidence in her resilience. But Rybakina's ascent is not noise — it tracks a player who has consistently performed at this level of the game.

What would have to be true for the current pricing to make sense? The money appears to hold two beliefs simultaneously: that Sabalenka is the most complete player in the draw and the likeliest single winner, but that Rybakina's ceiling is high enough — and their paths through the bracket close enough — that a final between them, or a Rybakina run to the title, is nearly as plausible as a Sabalenka coronation. Anyone else winning has been largely discounted by the field.

For fans and bettors alike, the most important development over the next several days will be whether Rybakina's upward move continues or stalls. If she crosses the 50% mark in the deeper market, the race formally inverts. If Sabalenka stabilizes and pushes back toward 60%, the original read — commanding favorite, legitimate challenger — reasserts itself. For now, the US Open women's draw is a two-player race with no clear separation, and the money is watching every match for the signal that breaks the deadlock.