'You play a match and you go home and you're still changing diapers. It's like a double life.'
Serena Williams said the work is never done for mothers who are also professional tennis players following her victory over fellow mom Tsvetana Pironkova in the US Open quarter-finals on Wednesday.
Williams fired down 20 aces en route to a hardfought 4-6, 6-3, 6-2 win over the Bulgarian, who had her first child in 2018 and defied expectations with a quarter-final run in her first tournament in three years.
"It just shows me how tough moms are," Williams said of Pironkova's performance.
"Whenever you can birth a baby, honestly, you can do anything and you saw that with Tsvetana today. She played unbelievable. I could barely win a match when I came back."
Pironkova agreed that it was difficult juggling her dual role.
"It's definitely not easy," she said earlier in the tournament.
"It's my first tournament back and right now I'm just happy to be playing. And having the opportunity for him to watch me play makes me really happy."
Williams, who gave birth to her daughter in 2017, could face another mother, Victoria Azarenka, in Thursday's semis.
"I think I'm most influenced by moms," said Williams.
"How do you do it? You play a match and you go home and you're still changing diapers. It's like a double life," she said. "It's really surreal."
The 38-year-old American, who is two wins away from a record-tying 24th Grand Slam singles title, said motherhood had given her strength.
"I think when you're a mom, you overcome so much just to become that and to be that," she said.
"And age is really how you feel mentally and how your body is doing and how you physically are able to keep up.
"If you think of it as just a number, then that's all it is."