Venus, who is the 2002, 2013 and 2015 French Open winner, reached the fourth round with a straight-sets defeat of Elise Mertens, 6-3, 6-1.
Serena, who is a 23-time major winner, was chic in a black dress and long floral kimono from Zara that retails for US$149. The outerwear features an open V-neckline, long sleeves, contrasting patch pocket, and a matching belt that ties around the waist.
On Thursday, Serena confirmed that she doesn’t know the sex of the baby she’s having with fiancé and Reddit co-founder Alexis Ohanian after fans of the mom-to-be freaked out when Venus referred to Serena’s baby as “she” — with many speculating that the older Williams sibling had accidentally revealed the gender of her future niece (or nephew). When asked what Serena’s child will call her, 36-year-old Venus told Eurosport on Wednesday, “She’s going to call me ‘favorite aunt.’ ”
In April, Serena announced the couple were expecting their first child together. One month later at the 2017 Met Gala in New York City, she and Ohanian told Vogue’s André Leon Talley that they’re waiting to see whether they’ll welcome a boy or a girl.
The mother-to-be had her last match at the Australian Open finals in January, where she won against Venus.
Williams and Ohanian were also in the stands for Venus’ match on May 31.
This story originally appeared on PEOPLE.com.