TORONTO (AP) — Serena Williams wore her game face when she stepped out into the stadium for her first match since telling the world she is ready to leave professional tennis. However, the game ended in defeat for the 23-time Grand Slam champion who lost to Belinda Bencic 6-2, 6-4.

While there were some familiar fist pumps and yells of "Come on!" during competition, it was only afterward that Williams really allowed her feelings to show, her voice shaking and her eyes welling during an on-court interview when Bencic ceded the spotlight.

"A lot of emotions, obviously," Williams told spectators who offered her encouragement throughout the evening.

The second-round match at the hard-court tuneup for the US Open came a day after she announced "the countdown has begun" on her playing career, saying she wants to have another child and pursue business interests.

She did not state precisely what her last event will be, but did make it sound as if her final farewell will come at the US Open, which begins August 29 in New York. Williams has won the singles title at Flushing Meadows a half-dozen times — first in 1999; most recently in 2014 — to go along with seven championships apiece at Wimbledon and the Australian Open, plus three at the French Open.

"It's been a pretty interesting 24 hours," Williams said after Wednesday's match.

"I'm terrible at goodbyes," she added, her hand on her chest, "but goodbye, Toronto!"

Next up on her schedule is the Western & Southern Open in Cincinnati next week, another event that serves as preparation for the year's last Grand Slam tournament.

Williams, a three-time champion in Canada, started this match, fittingly enough, with an ace. Delivered another later in that game, too, showing off the superb serve that helped her to so many match victories, so many tournament titles, so many weeks at No. 1 in the rankings.

That elite ability showed up occasionally against Bencic, whether the trio of unreturnable serves to close out that opening game or a later putaway swinging volley accented with a shout and a tug on the brim of her white visor.

But because of a leg injury that sidelined her for the last half of 2021 and first half of 2022, she was playing for only the third time in the past 12 months. There were signs of that, as well, and of why Williams is no longer the dominant force she was for so long.

The breaks of her serve that were never quite so frequent when she was younger and at the height of her powers. The not-quite-on-target groundstrokes. The inability to offer up too much resistance while receiving serve; she only earned one break point in the first set, missing a return long to fritter away that chance, and none in the second.

"I wish I could have played better," Williams said, "but Belinda played so well today."

It did not help Williams that she was facing an opponent 15 years her junior and quite talented, to boot: Bencic is ranked 12th, won a gold medal for Switzerland at the Tokyo Olympics last year and has been a Grand Slam semifinalist.

"It's always an honor to be on the court with her," Bencic said, "and that's why I think tonight is about her."