Jankovic received a first-round bye and was in action for the first time since being eliminated in the fourth round at Wimbledon by Tamarine Tanasugarn. Jankovic, who had reached the semifinals in both the Australian Open and French Open this year, got past King 7-5, 6-2.
That set up a third-round meeting with Melinda Czink, who defeated Olga Savchuk 6-4, 2-6, 6-4.
Dinara Safina, the fourth seed, advanced with a 6-2, 6-2 decision over Shuai Peng and No. 5 seed Vera Zvonareva won over Jill Craybas 6-4, 7-6 (7-2).
In the day's biggest surprise, Ai Sugiyama eliminated seventh-seeded Patty Schnyder 6-4, 7-5.