Six women from the U.S. won Wednesday at the All England Club, including two real surprises.
158th-ranked qualifier Bethanie Mattek-Sands eliminated No. 7 Ana Ivanovic, the 2009 French Open champion, 6-3, 6-4; and 47th-ranked CoCo Vandeweghe, the niece of former NBA player and executive Kiki, beat No. 11 Karolina Pliskova 7-6 (5), 6-4.
Also advancing: No. 21 Madison Keys, who finished off a match suspended because of darkness at 2-all in the third set a night earlier, and Sloane Stephens.
Rock Island's Keys downed Stefanie Voegele of Switzerland 6-7 (6), 6-3, 6-4.
Both Williams sisters won second-round matches as well: 16th-seeded Venus beat 95th-ranked Yulia Putintseva of Kazakhstan 7-6 (5), 6-4, while top-seeded Serena defeated 93rd-ranked Timea Babos of Hungary 6-4, 6-1.
Two more wins, and the siblings will meet in the fourth round.
"She poses a big threat for me," Serena said about Venus.
They pulled out of doubles on Tuesday, citing "soreness" for Serena, who wants to focus on her pursuit of a fourth consecutive Grand Slam title.
LONDON — Down a break at 3-1 in the first set, defending champion Novak Djokovic came to life and reasserted his dominance on a sweltering day at Wimbledon.
Running off 13 points in a row, Djokovic seized command and stayed in front the rest of the way on Centre Court as he beat Finland's Jarkko Nieminen 6-4, 6-2, 6-3 on Wednesday to reach the third round of Wimbledon on one of the hottest days ever at the All England Club.
American, No. 21 Madison Keys of Rock Island, downed Stefanie Voegele of Switzerland 6-7 (6), 6-3, 6-4 in the women's division.
Nieminen started fast, breaking serve in the opening game and going up 3-1. But the top-ranked Djokovic won the next three games, including two at love, and never let Nieminen back into the match.
"At the beginning of the match, he came out firing some incredible shots," Djokovic said. "He made I think four winners in the first game, four or five in the second game. He was a break up but I managed to regroup, play some good tennis and get the control on my side."
It was the final match at Wimbledon for the 33-year-old Nieminen, who announced earlier this month that he will be retiring at the end of the year.
Djokovic gave Nieminen a warm embrace at the net and joined the Centre Crowd in applauding for the Finn as they walked off the court. Nieminen waved to the crowd and kissed his fingers and patted the grass.
"It's his last Wimbledon, so I was just congratulating him on a terrific career," Djokovic said. "He's been around for so many years. A very, very nice guy, one of the nicest guys off the court. He's a fighter on the court, so it was a pleasure to be the last player to play him at Wimbledon."
Djokovic, who also won Wimbledon in 2011 and is bidding for a ninth Grand Slam title, broke five times and never faced a break point after the first game. He compiled 38 winners to just 15 for Nieminen.
"It was very solid," he said.
Djokovic was first up on Centre Court on a day that forecasters said could be the hottest recorded day in Wimbledon history. Temperatures were hovering around 34 degrees C (93 degrees F) and could reach as high as 35 C (96 F), which would beat the previous record of 34.6 C (94.28 F) in the summer of 1976.
"On this warm day, it's good to spend a little bit less time (playing) than maybe what is possible," Djokovic said.
The men's field lost one of its top players Wednesday when fifth-seeded Kei Nishikori — who could have faced Djokovic in the quarterfinals — withdrew before his scheduled Centre Court meeting with Santiago Giraldo of Colombia.
Nishikori was forced out by an injury to his left calf, which he sustained in the grass-court tournament in Halle, Germany, two weeks ago. He aggravated the "small tear" during a five-set victory over Simone Bolelli on Monday.
"It was hurting just walking and running, so I decide not to play today," said Asia's top men's player, who reached the U.S. Open final last year.
One of the rising stars in men's tennis knocked out one of the game's veterans.
Seventh-seeded Milos Raonic served 29 aces and held off Germany's Tommy Haas 6-0, 6-2, 6-7 (5), 7-6 (4). The 24-year-old Canadian, who reached the semifinals last year, saved all three break points against him.
The 37-year-old Haas on Monday became the oldest man to win a match at Wimbledon since Jimmy Connors in 1991. His loss Wednesday kept him from becoming the oldest man to reach the third round at a Grand Slam since Connors at the 1991 U.S. Open at the age of 39.
In women's play, 2004 champion and fourth-seeded Maria Sharapova advanced by beating Dutch qualifier Richel Hogenkamp 6-3, 6-1 on Court 2. The Russian had eight double-faults but also 23 winners.
Coco Vandeweghe of the United States made it to the third round for the first time, upsetting 11th-seeded Karolina Pliskova of the Czech Republic 7-6 (5), 6-4. Vandeweghe will next face 22nd-seeded Sam Stosur, the 2011 U.S. Open champion.
In early men's matches, 11th-seeded Grigor Dimitrov beat Steve Johnson of the United States 7-6 (8), 6-2, 7-6 (2). Dimitrov reached the semifinals last year before losing to Djokovic.
Other men's winners included No. 16 David Goffin, No. 17 John Isner, No. 21 Richard Gasquet, No. 26 Nick Kyrgios and No. 27 Bernard Tomic.