Top seed and defending champion Victoria Azarenka was on the ropes in her third-round match at the Australian Open, but she overcame American Jamie Hampton in three sets.
American Serena Williams, a five-time Aussie champ, also reached the fourth round Saturday thanks to a 6-1, 6-3 victory over Japan's Ayumi Morita.
Azarenka's 6-4, 4-6, 6-2 win came only after the native of Belarus rallied against Hampton, who was suffering from chronic back problems during the match. After the encounter, Hampton revealed she had a pair of herniated disks in her lower back.
"Hurt my back last year at the French Open pretty badly," Hampton said. "It's something I deal with day to day, and, yeah, it was hurting. Normally when my back starts hurting I start cramping."
Hampton, ranked 63rd in the world, was ahead 2-1 in the final set, but she couldn't convert key break point opportunities and suffered 47 unforced errors. Even being down 4-2 in that last set, Hampton raced to a 40-0 lead in the seventh game, but Azarenka saved all three break point chances and then finished off the match in 2 hours, 9 minutes.
"I think she surprised everybody a little bit today," Azarenka said. "I didn't really see her play before, but my coach watched and he said she didn't play like that other matches that he saw."
Williams recorded the fifth-fastest serve in the history of women's tennis, rocketing one 128.7 mph in a quick first set. Morita took the first three games of the second before Williams came storming back in dominating fashion.
"Today was actually a really good match for me. I was involved in a lot of longer points, something I definitely wanted," Williams said.
The 15-time Grand Slam champion Williams is the reigning Wimbledon and U.S. Open champ who is seeking a third straight major title.
Caroline Wozniacki, the 10th seed from Denmark, topped Ukraine's Lesia Tsurenko, 6-4, 6-3, and will next play Russian veteran Svetlana Kuznetsova. The two-time major champion is unseeded this fortnight and advanced Saturday with a 6-2, 4-6, 6-3 win over Spain's Carla Suarez Navarro.
Also Saturday, 14th-seeded Russian Maria Kirilenko disposed of 20th-seeded Belgian Yanina Wickmayer, 7-6 (7-4), 6-3. Kirilenko next faces Williams, who holds a 5-0 all-time advantage against the Russian.
Russian Elena Vesnina upended 16th-seeded Italian Roberta Vinci, 4-6, 7-6 (7-4), 6-4. Vesnina faces Azarenka in the round-of-16.
American Sloane Stephens also moved on with a 7-5, 6-3 win over fellow teenager Laura Robson, who had knocked out eighth-seeded Petra Kvitova in the second round. Stephens will next play Serbia's Bojana Jovanovski, a 6-2, 7-6 (7-3) winner over Japanese veteran Kimiko Date-Krumm.
The fourth round opens Sunday in Melbourne with a quartet of matches.
Second-seeded Maria Sharapova, coming off a 6-1, 6-3 win over Venus Williams after opening her stay with a pair of double-bagel victories in the first two rounds, will try to avoid a letdown against Belgium's Kirsten Flipkens.
Also, fourth-seeded Agnieszka Radwanska takes her perfect 2013 record into Rod Laver Arena against former world No. 1 Ana Ivanovic, while fifth-seeded Angelique Kerber meets Ekaterina Makarova and sixth-seeded Li Na faces Julia Goerges.