"I just need to ... relax and do what I can do," Williams said, referring again to her deep thoughts from the morning.

"I was calm today," she said, then rolled her eyes and added: "It's a day-to-day basis with me. We all know that. I'm far from perfect."

Williams has been this close to adding to her title total before: In 2018, her first season back on tour after the birth of her daughter, Olympia, Williams reached the finals at Wimbledon and the US Open but lost each time.

That has left her Grand Slam total at 23, a record for the professional era that she established when she won the 2017 Australian Open while pregnant — but one fewer than Margaret Court accumulated while playing part of her career against amateur competition.

At the All England Club, she was beaten by Angelique Kerber. At Flushing Meadows, she was outplayed by Naomi Osaka in a match that descended into chaos after Williams was docked a game for a heated argument with the chair umpire. She said in a first-person essay she wrote for Harper's Bazaar that she met with a therapist and wrote to Osaka to apologize for the whole episode.

A rare show of emotion from Williams on Thursday could have been the semifinal's turning point.

Ahead 2-1 in the first set while Strycova served at 30-all, Williams sailed a backhand return way long and let out a cry of "Aaaaah!"Maybe that got her going. Williams seized seven points in a row and 16 of 20 to close out that set.

Halep seemed headed for a long day when her semifinal against Svitolina began with a pair of games encompassing 32 points across 20 minutes. Five of the first 11 points lasted at least 10 strokes; two went 23.

Soon enough, though, Halep was in control.

Now comes a tougher task: beating Williams.