No. 1 Zverev reaches US Open semifinals and will face Khachanov after Blockx's injuries

Alexander Zverev, of Germany, reacts after winning a point against Botic van de Zandschulp, of the Netherlands, during the quarterfinal round of the U.S. Open tennis championships, Wednesday, Sept. 9, 2026, in New York. (AP Photo/Adam Hunger)

Alexander Blockx, of Belgium, left, meets Karen Khachanov, of Russia, at the net after Blockx was forced to retire due to an apparent injury during the quarterfinal round of the U.S. Open tennis championships, Wednesday, Sept. 9, 2026, in New York. (AP Photo/Kirsty Wigglesworth)

Alexander Blockx, of Belgium, has his back worked on during a medical timeout during a match against Karen Khachanov, of Russia, during the quarterfinal round of the U.S. Open tennis championships, Wednesday, Sept. 9, 2026, in New York. (AP Photo/Kirsty Wigglesworth)

Alexander Blockx, of Belgium, has his foot checked during a medical timeout during a match against Karen Khachanov, of Russia, during the quarterfinal round of the U.S. Open tennis championships, Wednesday, Sept. 9, 2026, in New York. (AP Photo/Kirsty Wigglesworth)

Karen Khachanov, of Russia, celebrates on the court after winning a match against Alexander Blockx, of Belgium, during the quarterfinal round of the U.S. Open tennis championships, Wednesday, Sept. 9, 2026, in New York. (AP Photo/Kirsty Wigglesworth)