Serena and Venus Williams aren't ready to tell the world when they will return to the tennis tour.

The sisters, who own a combined 20 Grand Slam singles titles, declined to say yesterday when they will compete next.

Venus hasn't played since January because of a hip injury; Serena has been out since July after two foot operations, then blood clots in her lung.

They were on adjacent courts yesterday, offering coaching tips and playing points against kids aged 7 to 17 during a 45-minute clinic to help celebrate the 10th anniversary of the Southeast Tennis and Learning Center.

"I'm feeling better. Just starting training. I'm a little later than I suspected and hoped," said Serena, who resumed practicing a little more than two weeks ago. "But it's going steady. Slow and steady, I think, always works out when it's a race."

Her last competitive match came when she won her fourth Wimbledon title last summer; she's missed the last two Grand Slams.

The next major is the French Open, which starts on May 22.

"It's a great event, and we definitely want to be there," Venus said. "We just take it week by week, evaluating, and the good part is we both get better every week."

Both sisters moved around the court without any visible hitches yesterday.

Their connection to the center dates to before the US$5.1 million facility was built, when former Washington D.C. first lady Cora Masters Barry, the center's CEO, spoke to the Williams' mother about plans for the center. Their older sister, Isha Price, is a member of the center's board.

"The center is so important, because for us, it brings us full circle, growing up in Compton, California. And coming back to here is similar, because we see young people who really are us," Venus said. "It's a great opportunity for us to just really stay grounded and continue to do what's important, which is to give back."

Standing nearby as Serena ran kids through dills, Barry said: "It just shows, first of all, that Venus and Serena get who these kids are, as it relates to their beginnings and where they came from. And the kids know that - they get the connection. The kids are pleased by it and inspired by it."