US Open: Serena Williams reveals pre-match routine with daughter Olympia

Serena Williams has revealed the pre-match routine she goes through with her young daughter Olympia. 

Williams set up a third-round showdown at the US Open against her older sister after hitting 13 aces and overwhelming 101st-ranked Carina Witthoeft of Germany 6-2 6-2 in a little more than an hour.

After the match, she gave some insight into her life being a professional tennis player and new mother, and how her daughter helps her get ready before a clash on court. 

"It was good today, I had a little extra time," Williams said.

"When I get ready for a match I sit Olympia in the sink and she plays with my makeup and all my brushes and she tries to eat the soap. So I need to tell her, 'You can't eat the soap, honey.'

"It's amazing, I love it. We always stay together and we always get ready together and she has a little baby doll. So I call her my grand daughter. Her name is Kway Kway. 

"It's fun. I just love to have fun with her and I'm still a kid at heart so it's like we're really enjoying our time together."

Venus Williams advanced with a straight-set victory earlier on Wednesday. This Williams vs. Williams matchup will be the earliest they've faced each other at a grand slam tournament in 20 years.

Serena leads Venus 17-12 overall and 15-10 at majors. Two-time champion Venus beat Italy's Camila Giorgi 6-4 7-5.

Venus, seeded 16th, powered through the first set but appeared to lose energy toward the end of the second in broiling conditions inside the newly built Louis Armstrong Stadium. She said the crowd's encouragement had helped her.

"I felt the energy, definitely," Venus said. "That love-40 game at four all was not looking good and you guys really got me through that."

- with AAP