Serena Williams has returned to a tennis court.
She says Tuesday is her ``first day back'' after a series of health problems, including blood clots in her lung.
Williams tweeted a photo of herself with a racket in hand, and her agent, Jill Smoller, confirmed the 29-year-old American put in some work Tuesday.
Smoller wrote in an email to The Associated Press that Williams is ``taking it day by day depending on how she's feeling.''
The 13-time Grand Slam singles champion and former No. 1-ranked player has not played an official match since she won the title at Wimbledon in July.
She hasn't said when she will return to the tour.