(ANJA NIEDRINGHAUS ~ Associated Press)
Nearly three hours later, following a timely rain delay, she hobbled gallantly into the quarterfinals by beating Daniela Hantuchova 6-2, 6-7 (2), 6-2.
"I've never dealt with such pain," Williams said. "I can't believe I won, really."
When the rain came Monday, Williams was a set up but trailing 4-2 in the second-set tiebreaker. She limped off the court without bothering to fetch her tennis bag.
"I couldn't move before the rain," she said. "I was definitely saved by the rain."
"It's so hard to play against somebody that is struggling, and you kind of feel sorry," Hantuchova said. "I lost it. I had my chances."
Hantuchova shanked several shots down the stretch, including one in the rally where she lost serve to fall behind 4-2. Williams frequently punctuated points by screaming, "Come on!"
"I was going to die trying," Williams said. "I figured my heart wouldn't give out, so I had a good chance of making it."
On the final point, she whacked a confident backhand return that Hantuchova couldn't handle. Williams looked to the still-threatening sky and blew a kiss in gratitude toward the weather.
"I've been looking forward to this match since the draw came out," Williams said. "I can only hope and pray that I can make it."
Henin, seeking the only Grand Slam title she has yet to win, beat No. 15-seeded Patty Schnyder 6-2, 6-2.
Williams' sister, Venus, made it to the fourth round despite a performance so filled with errors she drew criticism from her father.
The three-time champion rallied past Akiko Morigami 6-2, 3-6, 7-5 in a match suspended Saturday. And she did it even though she faced 23 break points, double-faulted 14 times and trailed 5-3 in the third set.
Serena Williams' injury, described by the WTA Tour as a spasm-induced left calf strain, struck after Hantuchova hit a forehand winner for a 5-5, 30-15 lead in the set. Williams grabbed her calf, tapped it three times with her racket head and fell to the grass.
She remained down for seven minutes. While a trainer massaged the calf, Williams grimaced, then screamed in pain.
She kept playing for another 11 minutes, wiping away tears before one point while hitting shots weakly and walking stiffly in pursuit of the ball. But she managed to hold for 6-all, then won the last two points before the delay.
Some Centre Court fans cheered the interruption, pleased to see Williams rewarded for her valiant attempt to keep playing. She said she took advantage of the break to receive treatment with ice and massages, and drank a lot of liquids.
Williams' mother and coach, Oracene Price, said she advised her daughter not to continue.
"I thought about not finishing, but very briefly," Williams said. "I thought I wouldn't be able to live with myself if I hadn't at least tried."
The bizarre match even included a bathroom controversy. In the final set Williams requested a break leading 3-2, but chair umpire Kader Nouni told her to wait until Hantuchova served.
"I've been drinking a lot of liquids, so I have to use the bathroom," Williams told Nouni. "I can't go on a changeover? It won't take me long. I have to use the bathroom. I can't use the bathroom?"
Williams never did take a break.
Venus will next go against 2004 champion Maria Sharapova, one of only two players to win Saturday in the rain-plagued tournament. Venus trailed 4-1 in the second set when her match was halted.
Henin needed only 56 minutes to beat the No. 15-seeded Schnyder. Henin has lost 15 games in four rounds.
"I did my job perfectly until now," she said.
In the completion of third-round matches suspended Saturday, No. 5-seeded Svetlana Kuznetsova beat Agnieszka Radwanska 6-2, 6-3; No. 6 Ana Ivanovic defeated Aravane Rezai 6-3, 6-2; No. 11 Nadia Petrova swept Virginia Ruano Pascual 6-3, 7-6 (3); and No. 14 Nicole Vaidisova beat Victoria Azarenka 6-4, 6-2.
No. 12 Elena Dementieva lost to 16-year-old Tamira Paszek of Austria 3-6, 6-2, 6-3.
Rain has caused an interruption on six of the first seven days of the tournament.
In men's third-round play, 2006 runner-up Rafael Nadal was one point from victory when he hit a cross-court forehand barely wide. His match with Robin Soderling was immediately halted by rain with the score 7-all in the third-set tiebreaker.
Play resumed but then was stopped for the night with Nadal leading 6-4, 6-4, 6-7 (7), 4-6, 2-0.
No. 7 Tomas Berdych beat Lee Hyung-taik 6-4, 7-6 (2), 7-6 (3). No. 10 Marcos Baghdatis defeated No. 23 David Nalbandian 6-2, 7-5, 6-0.