The former world No. 1 Ivanovic erased fourth-seeded Italian Roberta Vinci 6-3, 6-3 in 70 minutes, while the Russian Petrova handled second-seeded Chinese Peng Shuai 6-4, 6-3 in just under an hour-and-a-half on Day 1.
Four opening-round matches here will produce four semifinalists at this eight- player, four-day event on the hardcourts at Westin Resort Nusa Dua. The wild card Ivanovic will face Petrova in one of the semis on Saturday. The Serbian Ivanovic is 6-5 lifetime against Petrova, including a 1-1 mark this season.
Friday's matches will pit top-seeded French slugger Marion Bartoli against Spaniard Anabel Medina Garrigues and third-seeded German Sabine Lisicki versus former top-10 performer Daniela Hantuchova of Slovakia.
The winner of this $600,000 third-year tournament will collect $210,000. It features the six highest-ranked players who have won a title during the year but failed to qualify for the WTA Championships and two wild cards.
This is the final WTA event of 2011.