Belgium's Yanina Wickmayer labored past Kai-Chen Chang 7-5, 2-6, 7-5 in the first round of the Stanford Classic on Monday but all eyes will be on Wimbledon champion Serena Williams who begins her title defense on Wednesday.
Fifth seed Wickmayer, ranked 37 in the world, had to work really hard to remain on course for her first WTA title of the year. Her struggle was almost identical to her three-set defeat against Tamira Paszek of Austria in the third round of Wimbledon last month.
South African Chanelle Scheepers joined her in the second round after a 6-4, 6-4 win over American Grace Min.
For the sixth seed, it was her first victory since she was bounced from the opening round of Wimbledon.
The hardcourt tournament's main attraction is Williams who won her 14th singles Grand Slam title in Wimbledon on Saturday.
Williams will open against the winner of 19-year-old US player Nicole Gibbs and Thailand's Noppawan Lertcheewakarn.
Other opening-round winners at the Stanford Classic included Michelle Larcher De Brito and Heather Watson.