"I'm only in my third one back", said Williams, who won the 2017 Australian Open while pregnant with her daughter, Olympia.
The 25-year-old Stephens, meanwhile, was last but not least on the women's side on Sunday, showcasing smarts and striking in her bout with No. 15 Elise Mertens.
After one of those Williams sisters showdowns that rarely fail to disappoint, we are back to the old debate at a Grand Slam event about who might be able to stop Serena.
"I think society puts it out there that you'll just kind of snap back and that's just a myth".
She next meets Karolina Pliskova in the quarter finals. "I worked really hard on that". Williams extended her head-to-head record against the Estonian to 5-0, despite dropping her first set against her opponent in their five meetings.
After calling a clinical third-round victory over elder sister Venus the best tennis she's played since her return, Williams said she's feeling no pressure to perform. She would break again for a 5-1 lead, then pound two aces in the next service game to wrap up the first set in 31 minutes.
George Bush turns candy man for Michelle Obama at senator McCain's funeral
In Phoenix, Davis read a posthumous statement from McCain that did not spare Trump . "He was a great man", she said. The White House did not answer questions about whether Trump played golf or if he watched the service from afar.
When she ripped a backhand victor to claim the third set's opening game Sunday, Williams let out her loudest shout of the day, leaning forward and rocking both arms. But Kanepi produced two big serves to save break points and then clinched it on her second set point.
The determination to come home strongly was evident from Williams, who let out a roar after ripping a backhand cross court to hold serve in the opening game of the deciding set.
"First of all, I served really, really well today", Thiem said.
Yet they are now the only single-figure seeds still in contention after Elina Svitolina lost in three sets to Anastasija Sevastova.
Asked if she was considering having another child, Williams said: "I've obviously thought about having more kids and it will happen, God willing, in time". The American would win the next two games, but she couldn't find another break and after fighting off two set points saw Kanepi knot the match on her third chance.
"Serena is probably the best player that I have ever seen on a tennis court on the women's tour", Rafael Nadal, the No. 1 men's seed, said after his four-set win.
I feel like we want it so bad now. They had combined for eight titles in Flushing Meadows, six by Serena, and each had beaten the other in a US Open final. I'm feeling great now, too.