US Open Men's & Women's Singles Round of 16 Picks, Prediction, Odds, and Line Movement for Monday September 7 2026

The second half of the U.S. Open Round of 16 takes center stage Monday in New York, with Naomi Osaka facing Elena Rybakina in the marquee women's matchup and Francisco Cerundolo meeting Alexander Blockx after both men produced major third-round upsets.

Rybakina has yet to drop a set in the tournament, while Osaka has needed three sets in each of her last two matches. Cerundolo, meanwhile, comes off a dramatic five-set comeback against Taylor Fritz, and Blockx is playing the best tennis of his young career after eliminating Flavio Cobolli.

U.S. Open Round of 16 Best Bet

• Elena Rybakina ML: -137

Naomi Osaka vs Elena Rybakina Preview

Rybakina has taken the cleaner route into the fourth round. The No. 2 seed is 6-0 in sets through three matches and most recently defeated Yuliia Starodubtseva 7-6, 6-3. She has spent only four hours and 14 minutes on court during the tournament, giving her a significant workload advantage heading into Monday.

Osaka has had to work considerably harder. After opening with a pair of tiebreaks against Anastasia Zakharova, she needed three sets against Katerina Siniakova and another three against Elise Mertens. Her 6-3, 3-6, 7-5 win over Mertens showed that she can still find her best tennis late in matches, but she has played nearly two and a half hours more than Rybakina through the opening three rounds.

Surface and Matchup

This matchup should be dictated by the first strike.

Both players possess elite serves and can take control with the next ball, but Rybakina has been doing that more consistently in New York. Her serve has allowed her to move through service games quickly and avoid the extended defensive stretches that can become dangerous against Osaka.

Their only previous meeting came less than a month ago on hard courts in Toronto. Osaka won the opening set and came within two points of victory in the second-set tiebreak before Rybakina recovered to win 4-6, 7-6, 6-4. That recent meeting is valuable because it showed how narrow the matchup can become when Osaka protects serve and attacks early.

The concern for Osaka is physical as well as tactical. She acknowledged after beating Mertens that she has been dealing with an Achilles issue since the grass season. She downplayed its severity, but against an opponent who can force explosive first steps with deep returns, even a minor limitation matters.

Odds and Line Movement

Rybakina was approximately 1.70 on the earlier market and is now available around -137, with Osaka near +117. That represents a small move toward Osaka rather than a rush to the favorite, leaving a slightly better Rybakina price than was available earlier.

What Will Decide the Match

Osaka needs to prevent Rybakina from establishing a predictable serving rhythm. If she can attack second serves and keep the Kazakh from holding routinely, this can look much like their Toronto battle.

Rybakina, however, enters fresher, has been more consistent through three rounds and already showed last month that she can withstand Osaka's best stretches without losing control of the match.

Prediction: Rybakina wins 2-1

Francisco Cerundolo vs Alexander Blockx Preview

Few players have taken a more dramatic route to the fourth round than Cerundolo. The Argentine fell behind Taylor Fritz by two sets before turning the match around and winning 3-6, 4-6, 6-3, 6-4, 6-4. It was the biggest result of his U.S. Open run and his first trip to the tournament's second week.

Blockx produced his own breakthrough against Cobolli, winning 3-6, 6-3, 6-0, 6-3. The 21-year-old Belgian described reaching the second week as one of his pre-tournament goals, and the quality of his serving against Cobolli suggests the run has not been accidental.

Surface and Matchup

Blockx wants this match played quickly. His serve and willingness to take the ball early can prevent Cerundolo from building points around his forehand.

Cerundolo prefers more time to shape rallies. If he can absorb Blockx's first attack and force additional neutral balls, his heavier forehand and experience should become more important as the match extends.

The Belgian already defeated Cerundolo in Madrid earlier this season, giving him some familiarity with the Argentine's patterns. Monday's hard-court conditions should suit Blockx even better if he continues serving at the level he showed against Cobolli.

Odds and Line Movement

Cerundolo was around 2.33 on the earlier board. Current prices have him roughly +142, with Blockx around -156. The matchup has therefore remained in a similar range, with the Belgian still a modest favorite.

Prediction: Blockx wins 3-2

Arthur Gea vs Botic van de Zandschulp Preview

Gea has already survived two demanding matches in New York, most recently beating Michael Zheng in five sets. The Frenchman dropped the middle two sets before responding to win the fourth and fifth, showing considerable composure for a player making his first deep Grand Slam run.

Van de Zandschulp arrives after an even more dramatic five-set win over Zizou Bergs. He has also already taken out Alex de Minaur in straight sets during this tournament, giving him the stronger body of high-level hard-court results entering Monday.

What Will Decide the Match

Gea's speed can create problems if van de Zandschulp becomes too aggressive too early, but the Dutchman owns the simpler path to holding serve. His height and flatter ball striking allow him to control the middle of the court, while Gea may need to defend more often before earning an opportunity to attack.

The current market has van de Zandschulp around -162 and Gea near +139, only a modest change from the earlier price that had Gea around 2.34.

Over five sets, van de Zandschulp's serving and ability to generate easier points should eventually provide the difference.

Prediction: Van de Zandschulp wins 3-1

Best Bet - Elena Rybakina ML -137

Osaka has the weapons to make this one of Monday's best matches, but Rybakina enters with the cleaner combination of form, freshness and recent matchup success.

She has not dropped a set in New York, has spent substantially less time on court and defeated Osaka on hard courts less than a month ago. Osaka's serve should keep the match competitive, but Rybakina's ability to produce cheap service points while consistently attacking from the first neutral ball gives her the stronger path over three sets.

Best Bet: Elena Rybakina ML -137

Prediction: Rybakina wins 2-1