“I have to say I felt every single one of you guys behind me, all 23,000,” she said to the crowd after defeating Kvitova. “I mean, that feels good. It feels amazing, and I didn’t want to let you guys down.”

Williams has been in a much more expansive mood at the U.S. Open than she was at Wimbledon, where her run to the final came shortly after her involvement in a fatal car crash in June in Florida, which led to the death of a passenger in the other vehicle. The family of the deceased has filed a wrongful-death lawsuit against her.

The subject, which brought her to tears at Wimbledon, has not been raised in news conferences here. She has also declined to answer questions about the birth of Serena Williams’s first child, but she has been much more expansive about her own tennis and her path back to Grand Slam contender after being diagnosed with the auto-immune disorder Sjogren’s Syndrome — a health problem she first revealed publicly after withdrawing from the 2011 U.S. Open after the first round.

“At the time, the frame of mind is as an athlete and as myself, I don’t accept limitations, so it took a while to accept some limitations,” she said. “But it doesn’t mean that the glass is half empty. I saw it as half full. Whatever I had, I had to do the best I could with that and to be the strongest that I could.”

Williams and Kvitova had not played since 2014, when Kvitova prevailed by 5-7, 7-6 (2), 7-5 in a third-round match at Wimbledon that drew rave reviews. Kvitova went on to win her second Wimbledon title.

Kvitova is a statuesque left-hander, Williams a statuesque right-hander, and their approaches to the game mirror each other. Both have huge reserves of natural power and both rarely find themselves in moments in which they are not eager to attack.