Second-seeded Dominika Cibulkova of Slovakia and top-seeded Marion Bartoli of France both advanced to the final of the $740,000 Mercury Insurance Open with victories on Saturday.
Cibulkova beat the fourth-seeded Russian in a long first-set tiebreaker then cruised the rest of the way to a 7-6 (10-8), 6-1 win in 96 minutes on the hardcourts at La Costa Resort and Spa.
Cibulkova shook off nine Petrova aces and moved to 3-1 all-time against the Russian, avenging a quarterfinal loss to her in an event in the Netherlands earlier this year.
She will face the top-seeded Bartoli in the final. Bartoli took down qualifier Yung-Jan Chan of Taiwan 1-6, 6-3, 6-3 in the other semifinal.
Chan upset third-seeded Serbian Jelena Jankovic on Friday to make the semis.
The 2012 Carlsbad champ will claim $96,000.