Maria Sharapova saved eight set points before finally grinding out a 6-2, 7-6 third-round victory over Maria Elena Camerin at the Nasdaq-100 Open on Sunday.
By contrast, Amelie Mauresmo made straightforward progress, defeating fellow Frenchwoman Marion Bartoli for the third time with a 6-4, 6-0 win.
Top seed Mauresmo now plays 14th-seeded Ana Ivanovic of Serbia and Montenegro, who beat Ukrainian Alona Bondarenko 6-3, 5-7, 6-3.
Sharapova, debuting a new black corset-look top, advanced despite making 38 unforced errors against the Italian ranked 79th. She faced a battle in the second set, trailing 1-4 before salvaging victory in one hour, 44 minutes with a backhand winner.
She now faces fellow Russian Maria Kirilenko, who defeated Viktoriya Kutuzova of the Ukraine 6-1, 6-4.
"I fought for it, I did a good job of fighting at the end," Sharapova told reporters. "When the day's not great, when you feel like you're not playing your best tennis, I still know that I can fight it out.
"I didn't really feel great out there today. I started off well and things were going my way and all of a sudden I just made a lot of unforced errors, especially with the wind."
In the men's draw, third seed David Nalbandian of Argentina fought back to defeat Czech Tomas Berdych 6-7, 6-1 6-0 to reach the fourth round.
Russian Nikolay Davydenko, seeded fifth, went through 2-6, 6-2, 7-5 against Cypriot Marcos Baghdatis, the Australian Open runner-up finishing the contest with two double faults.
Nalbandian won his fourth match out of five since returning from a month out with an abdominal injury suffered during the Davis Cup in February.
The Argentine, who beat world number one Roger Federer in the final of the Masters Cup last November, improved his record this season to 10-2 after 20-year-old Berdych's game fell apart in the second and third sets.
Nalbandian, an Australian Open semi-finalist this year, broke his opponent's serve five times.
Croatian Mario Ancic advanced with a 7-6, 6-7, 6-2 triumph over Florent Serra of France. Czech Radek Stepanek, the 15th seed, defeated Nicolas Massu of Chile 6-7, 7-6, 7-5.
Women's results: Round three
6-Elena Dementieva (Russia) beat Michaella Krajicek (Netherlands) 6-0 6-1
22-Tatiana Golovin (France) beat Elena Vesnina (Russia) 6-2 6-3
12-Svetlana Kuznetsova (Russia) beat 24-Martina Hingis (Switzerland) 3-6 6-1 7-6 (9)
7-Patty Schnyder (Switzerland) beat 28-Katarina Srebotnik (Slovenia) 7-6(3) 6-3
4-Maria Sharapova (Russia) beat Maria Elena Camerin (Italy) 6-2 7-6(2)
10-Anastasia Myskina (Russia) beat Victoria Azarenka (Belarus) 6-3 7-5
5-Nadia Petrova (Russia) beat Jamea Jackson (U.S.) 4-6 6-0 6-0
1-Amelie Mauresmo (France) beat 30-Marion Bartoli (France) 6-4 6-0
21-Ai Sugiyama (Japan) beat 15-Elena Likhovtseva (Russia) 3-6 7-5 6-0
Anna Chakvetadze (Russia) beat Virginie Razzano (France) 6-4 6-0
20-Maria Kirilenko (Russia) beat Viktoriya Kutuzova (Ukraine) 6-1 6-4
Eleni Daniilidou (Greece) beat 13-Daniela Hantuchova (Slovakia) 6-3 4-6 6-2
32-Sofia Arvidsson (Sweden) beat Meghann Shaughnessy (U.S.) 5-7 6-3 7-6(5)
Jill Craybas (U.S.) beat 27-Klara Koukalova (Czech Republic) 6-1 6-2
Jie Zheng (China) beat 16-Anna-Lena Groenefeld (Germany) 6-4 7-5
14-Ana Ivanovic (Serbia and Montenegro) beat Alona Bondarenko (Ukraine) 6-3 5-7 6-3
Men's results: Round three
Christophe Rochus (Belgium) beat 20-Robby Ginepri (U.S.) 4-6 7-5 6-3
Agustin Calleri (Argentina) beat Carlos Moya (Spain) 6-3 7-6(6)
6-Ivan Ljubicic (Croatia) beat 30-Filippo Volandri (Italy) 6-2 6-3
16-Nicolas Kiefer (Germany) beat 18-Fernando Gonzalez (Chile) 6-2 3-6 7-5
15-Radek Stepanek (Czech Republic) beat Nicolas Massu (Chile) 6-7(6) 7-6(5) 7-5
5-Nikolay Davydenko (Russia) beat 25-Marcos Baghdatis (Cyprus) 2-6 6-2 7-5
22-Mario Ancic (Croatia) beat Florent Serra (France) 7-6(4) 6-7(11) 6-2
3-David Nalbandian (Argentina) beat 26-Tomas Berdych (Czech Republic) 6-7(3) 6-1 6-0