Updated September 11, 2026
Alexander Zverev and Karen Khachanov meet Friday in the US Open semifinals, with Zverev arriving as the No. 1 seed and the clear favorite after his level rose sharply during the second week of this tournament. The German needed 5 sets in each of his first 2 matches, but he has since beaten Alejandro Tabilo, Luciano Darderi, and Botic van de Zandschulp without dropping a set. Khachanov is ranked No. 50 entering this stage of the tournament, but he knocked out No. 3 seed Felix Auger-Aliassime and survived a 5-set test against Learner Tien before advancing from his quarterfinal when Alexander Blockx retired.
Why Our Model Sees Value:
“The current price suggests that we could see a competitive 4-set or 5-set match, while Zverev's rapidly improving second-week level of play creates a larger chance of a straight-sets win or relatively short 4-set victory.”
Straight Sets Not Needed
The key distinction with this position is that Under 38.5 does not require Zverev to win in straight sets. A score such as 6-3, 6-4, 4-6, 6-3 totals exactly 38 games. That gives the Under several realistic 4-set paths in addition to nearly every conventional straight-sets result.
Zverev Dominating This Week
Polymarket's 57% price on Over 3.5 sets is understandable given Khachanov's hard-court history against Zverev and his strong tournament results, but the total-games market leaves room for four sets. Zverev has won his last 9 sets at this US Open. Two of those matches finished with only 25 games, while his quarterfinal against van de Zandschulp ended 6-2, 7-5, 6-1 for 27 games. Even if Khachanov makes Friday considerably closer, there is enough clearance between those results and 38.5 for the Under to survive one dropped set.
Recommended Prediction:
Under 38.5 Games
Current Market Price:
52¢
Model Win Probability:
57%
Market-Implied Probability:
52%
Model Edge:
5%
Buy Up To:
54¢
Model Trade Confidence:
80/100
Zverev's first week did little to inspire confidence in a semifinal run. Lorenzo Sonego pushed him for 4 hours and 52 minutes in Round 1 before Zverev escaped 6-4, 3-6, 6-7, 7-5, 6-4. Quentin Halys then extended him another 4 hours and 33 minutes in a second straight 5-set match. Zverev had already spent 9 hours and 26 minutes on court before his third-round meeting with Tabilo.
Since then, Zverev beat Tabilo 6-2, 7-6, 6-2, then dispatched Darderi 6-2, 6-2, 7-6. He followed those performances by defeating van de Zandschulp 6-2, 7-5, 6-1 in the quarterfinal. He has now recorded 3 consecutive straight-set victories and reached the semifinals at all 4 majors in 2026.
That progression is important. An Under as our Zverev vs Khachanov prediction would be far harder to justify if Zverev were still producing the uneven tennis seen against Sonego and Halys. Instead, the later rounds have featured much cleaner scorelines and an ability to turn close portions of sets into decisive finishes.
Calling Khachanov the world No. 50 would undersell what he has done in New York, even if it's true. He entered the tournament after losing 4 consecutive matches, but his US Open results have been much stronger. His biggest early breakthrough came against Auger-Aliassime, whom he defeated 6-7, 6-3, 6-2, 6-2. He later came from behind against Tien for a 7-5, 4-6, 6-7, 6-1, 6-4 fourth-round victory.
Khachanov's quarterfinal was considerably shorter. He led Blockx 6-2, 7-5, 3-2 when the Belgian retired after dealing with several physical issues. That means Khachanov did not have to complete another lengthy best-of-5 match before Friday's semifinal.
The additional rest helps Khachanov, but it does not automatically favor a high total. His path to the Over still probably requires him to protect his serve consistently enough to force several 12 or 13-game sets. If Zverev begins generating early return pressure, one lopsided set can make 39 games difficult to reach.
Zverev leads the career series 6-3 across 9 meetings. The matchup is more competitive on hard courts than the overall record initially suggests, since all 3 of Khachanov's victories have come on hard courts. Their most significant meeting was the 2021 Olympic gold-medal match, which Zverev won 6-3, 6-1. Their previous Grand Slam meeting came at Roland Garros in 2018 and lasted 5 sets.
More recently, Khachanov beat Zverev 6-3, 4-6, 7-6 in the 2025 Toronto semifinal after saving a match point. Zverev then led their Cincinnati meeting 7-5, 3-0 before Khachanov retired.
Khachanov has shown he can trade with Zverev from the baseline on hard courts and make individual sets very tight. Still, a best-of-5 match changes the calculation. Khachanov cannot simply produce one strong set. To send the total safely above 38.5 games, he needs sustained resistance across most of the afternoon.
Both players are 6-foot-6 right-handers who want to build points behind a heavy first serve. Zverev's advantage is his ability to defend unusually well for his size while remaining comfortable in extended backhand exchanges. Khachanov is at his best when he can shorten rallies with his forehand and dictate from inside the baseline.
Zverev did show one warning sign against van de Zandschulp, producing 5 double faults during an inconsistent start. Yet he still won in straight sets and took 3 consecutive games late in the second before dominating the third. That ability to win sets without playing his absolute best is particularly relevant to a games total.
Khachanov needs his first serve to keep him out of repeated neutral rallies. If his first-serve rate drops and Zverev regularly starts return points from a stable position, the German can create the type of 6-2 or 6-3 set that dramatically improves the Under's chances.
Khachanov's run deserves respect, and his hard-court record in this matchup is enough to prevent a very high-confidence call. The current Polymarket pricing, however, appears to lean too far into the possibility of a long semifinal. Zverev has gone from surviving consecutive 5-set matches to winning 9 consecutive sets, and his last 3 opponents have failed to force a fourth set.
The most likely match result is Zverev winning in 3 or 4 sets, with something in the range of 34 to 38 total games occupying a meaningful portion of our projections. At a 52% implied probability, Under 38.5 games offers a 5% edge based on a 57% projected win rate.
