Williams had little trouble winning her Japan Open first-round match, dispatching Jill Craybas, 6-3, 6-1.
But Kirilenko had company in the upset column as fourth-seeded Ai Sugiyama and No. 6-seeded Akiko Morigami disappointed local fans by falling. Sugiyama was taken out by qualifier Meng Yuan, 6-3, 6-3, and Alicia Molik routed Morigami, 6-1, 6-2.
Vania King beat Edina Gallovits, 6-2, 5-7, 7-5, and is to face Williams in the second round. Other first-round winners Tuesday were Abigail Spears, Aleksandra Wozniak, Elena Baltacha and Jelena Kostanic Tosic.
The tournament continues through Sunday when the champion will pick up $25,840.