Top-seeded Djokovic defeated No. 7 Tomas Berdych 7-6 (5), 6-4, 6-3, and eighth-seeded del Potro beat No. 4 David Ferrer 6-2, 6-4, 7-6 (5).
Neither man has dropped a set on the way to the final four. Djokovic is 8-3 lifetime against del Potro, who is in his first Wimbledon semifinal.
Del Potro hyperextended his heavily taped left knee on the fifth point of the match and rolled to the ground. He needed a medical timeout and was moving gingerly when play resumed. But he got two first-set breaks against Ferrer and didn't look back.