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.

Greeted by a standing ovation, the 23-time Grand Slam champion didn’t smile. She didn’t wave. She took a sip from a plastic bottle as she walked in. Some folks in the crowd captured the moment with the cameras on their cellphones. Others held aloft hand-drawn signs — oh, so many signs — with messages such as "Queen" or "Thank you."

No one knows exactly how many more matches Williams will play before she puts her rackets away for good, and the 40-year-old American exited the National Bank Open on Wednesday night with a 6-2, 6-4 loss to Belinda Bencic.