Updated

Melbourne, Australia (SportsNetwork.com) - Maria Sharapova survived, and in more ways than one on Thursday at the Australian Open.

Sharapova, the 2008 champion and this year's third seed, outlasted Italy's Karin Knapp 6-3, 4-6, 10-8 in a 3 1/2-hour marathon second-round match that was played in sweltering heat before the roof was closed at Rod Laver Arena.

"I'm really happy to get through," said Sharapova. "I really am. I worked really hard in the last few months and I wanted this match. I didn't play my best tennis. I didn't do many things well. I got through it, and sometimes that's what's important."

Also getting through to the third round were Victoria Azarenka and Agnieszka Radwanska, but in much easier fashion.

Azarenka, the two-time defending champion and second seed, claimed a 6-1, 6-4 triumph over Czech Barbora Zahlavova Strycova, while the fifth-seeded Radwanska notched a 6-0, 7-5 win over Olga Govortsova.

Sharapova and Knapp opened play Thursday at Laver Arena and the decision to close the roof and halt action on the outer courts because of oppressive heat was made during the match. Rules, therefore, stipulated that the match conclude before the roof could be closed.

The two gutted it out through a 108-degree temperature with high humidity.

Knapp had Sharapova on the ropes in the third set, holding an 8-7 lead, but the Russian's experience came through down the stretch.

After holding serve for 8-8, Sharapova broke Knapp to go on top before the four-time Grand Slam champ closed out the contest on her serve. It wasn't easy, however, as Sharapova gave Knapp three points with double-faults in the 18th game before finally prevailing on her fourth match point when Knapp missed on a backhand.

"I was up a set and a break and I had many opportunities to finish the match faster," noted Sharapova. "So I would have loved for it to finish faster, but that's what I got and I have to deal with the circumstances. I'm all right with that. I'm a competitor here, and I worked hard to get through that match. I will have to work just as hard to get through the next ones."

Next up for Sharapova, who was an Aussie Open runner-up in 2007 and 2012, will be 25th-seeded Alize Cornet of France after she earned a hard-fought 6-3, 4-6, 6-4 decision over Italy's Camila Giorgi.

Azarenka, who beat Sharapova for the 2012 title, opened the night session and played under the roof at Laver Arena. She had little trouble in a 34-minute first set, but struggled to polish off Zahlavova Strycova, needing nearly an hour to win the second set.

"There was just a moment when I just felt I dropped my intensity a little bit and was watching her a little bit too much," said Azarenka about the second set. "I'm glad I could just turn it around in the end and really get back into it and play the way I was playing in the first set."

Azarenka will encounter Austrian Yvonne Meusburger in the round of 32.

Radwanska had a similar match on Thursday, winning 25 of the 34 points played in a 24-minute first set. Govortsova made the four-time Aussie Open quarterfinalist work in the second set before ultimately falling.

"I started really well today," said Radwanska, who also was able to play indoors at Hisense Arena. "I think then she tried to play more aggressive in the second set and I think I did step backwards, unfortunately. Suddenly I was a break down. But just very happy that I could manage to win that second set and finish the match."

Next for Radwanska will be Russian Anastasia Pavlyuchenkova, a 6-2, 6-2 winner over Luxembourg's Mandy Minella.

Former world No. 1s Jelena Jankovic and Caroline Wozniacki also advanced, as did American Sloane Stephens.

The eighth-seeded Jankovic thumped Japan's Ayumi Morita 6-2, 6-0, while the 10th-seeded Wozniacki went the distance in a 6-0, 1-6, 6-2 triumph over American Christina McHale. Stephens, seeded 13th this year after her surprising semifinal run last year, rallied for a 3-6, 6-2, 7-5 win over Croatia's Ajla Tomljanovic.

Up next for Jankovic will be Japan's Kurumi Nara, who took out 32nd-seeded Slovak Magdalena Rybarikova 6-4, 6-3, while Wozniacki will next play Spain's Garbine Muguruza, a 6-3, 6-3 victor over Slovakia's Anna Schmiedlova, and Stephens will next face Ukrainian Elina Svitolina, who advanced with a 6-4, 7-5 win over Australia's Olivia Rogowska. The hot Muguruza is fresh off her first-ever WTA title in Hobart last week.

Eleventh-seeded Romanian Simona Halep bounced back from a slow start against American Varvara Lepchenko to claim a 4-6, 6-0, 6-1 win, setting up a third- round matchup with Kazakhstan's Zarina Diyas, who downed New Zealand's Marina Erakovic by a 6-4, 6-0 margin.

Carla Suarez Navarro needed a late rally to fend off Galina Voskoboeva of Kazakhstan, as the 16th-seeded Spaniard secured her place in the next round with a 7-6 (7-2), 3-6, 8-6 victory.

Slovakia's Dominika Cibulkova, the 20th seed, awaits Suarez Navarro in the third round after cruising to a 6-0, 6-1 win over Swiss Stefanie Voegele, and the aforementioned Meusburger dismissed 33rd-seeded Serb Bojana Jovanovski 3-6, 6-3, 6-2.

The excessive heat forced play on the outer courts to be suspended for a few hours and rain also delayed play.

The third round will commence Friday, including matches for five-time champion Serena Williams and two-time Aussie Open runner-up Li Na.

The world No. 1 and reigning U.S. and French Open champion Williams will face 31st-seeded Slovak Daniela Hantuchova, while the fourth-seeded Li will battle 26th-seded Czech Lucie Safarova. Li lost to Azarenka in last year's Melbourne finale.

Also on Friday, last week's Sydney runner-up, ninth-seeded German Angelique Kerber, will meet upstart American Alison Riske and 14th-seeded former world No. 1 Ana Ivanovic will tangle with 17th-seeded former U.S. Open champ and heavy Aussie crowd favorite Sam Stosur. The former French Open winner Ivanovic was an Aussie Open runner-up to Sharapova in 2008.