Time up for Rafael Nadal

Asked if she could explain what went wrong, a sullen Williams replied: “No. I can’t. I’m sorry. Any more questions?” And a moment later, a white baseball cap pulled low over her eyes, she added: “She made a lot of lucky shots and I made a lot of errors.”

That high-powered match was followed by the biggest surprise so far on the men’s side: No. 2 Rafael Nadal’s body broke down and he lost to fellow Spaniard No. 15 David Ferrer, who reached his first US Open quarter final. Ferrer’s 6-7 (3-7), 6-4, 7-6 (7-4), 6-2 victory means there won’t be a third consecutive major final between Nadal and No. 1 Roger Federer.

Ferrer did something one rarely sees: He ran Nadal ragged. After losing the next-to-last game, Nadal winced and dropped to the court, sitting with legs stretched out and head bowed. Nadal is a three-time French Open champion and a two-time Wimbledon runner-up, but he’s never been past the US Open quarter finals.

While the formerly No. 1-ranked Williams is the active leader among women with eight Grand Slam titles, current No. 1 Henin will have a chance to get her seventh major.

Henin’s next opponent could be another Williams: Serena’s older sister, Venus, faces No. 3 Jelena Jankovic in the quarter finals.

“Playing Serena is really exciting for me,” Henin said after compiling a 30-17 edge in winners. “I was really happy about the second set. I played much more aggressive.” Not much question for whom Henin will be rooting—she’s 1-7 against Venus Williams, 7-0 against Jankovic.

“Every match is a final for me now,” Henin said. “If I have to play Venus, it will be a good challenge for me to play both sisters in the same tournament.”

Henin beat the younger Williams at the French Open en route to her fourth title in five years there, and again at Wimbledon. “I got a lot of confidence in Paris and London,” she said. Their matchup at Wimbledon in July didn’t feature Williams at her absolute best: She could barely hit backhands after spraining her left thumb and hurting her left calf in the previous round. Because of the thumb, Williams withdrew from every event she was scheduled to play in the one-and-a-half months between Wimbledon and the US Open. “I don’t think that affected me,” she said. “I don’t think it did. Maybe it did.”

Yesterday’s match featured brilliant play by both and the difference was made by Henin’s ability to steer Williams this way and that along the baseline until the Belgian could find an opening for her smooth backhand or a well-placed forehand. Repeatedly, especially in the second set, Henin wrong-footed Williams to end a point. The No. 3-seeded Djokovic reached the US Open quarter finals for the first time by beating No. 23 Juan Monaco 7-5, 7-6 (7-2), 6-7 (6-8), 6-1 in a match that included the unusual sight of Monaco losing a point because a ball fell out of his shorts.

“I went nuts! I was cursing at me. I was yelling at my pants,” Monaco said. He was serving while ahead 5-3 in the third-set tie-breaker when the players settled into an extended baseline exchange. As Monaco whipped a shot, an extra yellow ball he had tucked away in case of a fault popped out of his pocket – the second time it happened during the match. He stopped playing, dropped his racket, doubled over and screamed, knowing what was coming.

“Right away I knew I lost that point. It’s very weird,” Monaco said. “That sort of thing cannot happen twice in the same match.” Chair umpire Jake Garner had no choice. “By rule,” he announced, “he loses the point.” Djokovic gladly took it.

Djokovic now faces No. 17 Carlos Moya. The 31-year-old Moya is the oldest man still in the tournament, and the player he beat 7-5, 6-2, 6-7 (5-7), 6-4 yesterday, 19-year-old Ernests Gulbis of Latvia, was the youngest left. After Williams and Henin were done, David Ferrer beat Nadal. Ferrer will now meet No. 20 Juan Ignacio Chela, who got past Stanislas Wawrinka in five sets 4-6, 6-2, 7-6 (8-6), 1-6, 6-4.

Like Djokovic, Chela reached his first US Open quarter final. Moya, however, has been there before—although not since 1998. “Still beating these young guys,” Moya said. “I feel like 20 year old.”