Alexander Blockx impresses at US Open, but rib pain casts doubt on his run

Historic breakthrough for Belgium

At the 2026 ATP US Open, held at the Billie Jean King USTA National Tennis Center, 21-year-old Belgian Alexander Blockx made history on Monday by becoming the first player from his country ever to reach the US Open quarterfinals, and the youngest Belgian to reach this stage at any Grand Slam. World No. 34 Blockx faces experienced Russian Karen Khachanov on Wednesday; the two have never met before (head-to-head 0-0).

From waffles and burgers to the top 50

According to Eurosport, Blockx's route to this success has not been a straight line. The 1.94m-tall player had a stellar junior career — topping Europe's rankings in several age categories and winning the Australian Open junior title at 17 — but a growth spurt slowed his progress for a while. In autumn 2025, after losing in the second round of three consecutive Challenger events and in the final qualifying round of the Brussels ATP 250, Blockx made a radical decision: he stopped thinking about tennis for a week and, as he told the ATP website, "gorged on waffles and burgers" to clear his head. He then won a Challenger title in Bratislava, and his career has risen sharply since — qualification for the Next Gen ATP Finals, a climb into the top 100 and then the top 50, a semifinal at the Madrid Masters 1000, and his first ATP tour final in Estoril. In May he had to retire early from the French Open after spraining his ankle in a training session with Joao Fonseca; now in New York he has already won more Grand Slam matches than in the rest of his career combined.

Rib pain raises doubts

Ahead of the quarterfinal, attention has turned to Blockx's physical condition. During his round-of-16 win over Francisco Cerundolo, he needed medication mid-match and continued to feel pain afterward. He admitted he felt sharp pain in his ribs through the first three sets and that a loss in the third set might well have forced him to retire. Khachanov spoke respectfully of his opponent before the match, calling him a dangerous player with a powerful serve and a solid baseline game. The numbers back that up: Blockx leads all quarterfinalists in points won on first serve (82%), and his serve has been clocked at 218 km/h, the second-fastest among the last eight, behind only Alexander Zverev. Still, as Last Word On Sports notes, bookmakers clearly favor Khachanov, with a straight-sets win considered a strong possibility given lingering doubts about Blockx's fitness.

Zverev's smooth run continues

In the tournament's other quarterfinal, top seed Alexander Zverev — the de facto favorite with injured world No. 1 Jannik Sinner not competing — faces Botic van de Zandschulp, who played over five hours in his previous match compared with Zverev's three sets. Should Zverev win, his likely semifinal opponent would be either Khachanov or Blockx, neither of whom is ranked inside the world's top 20 — giving Zverev one of the more favorable paths to a Grand Slam final in recent memory.