The American, now 32, is often asked about retirement, even though she is in some of the best form of her life and shows no sign of slowing down.

Martina Navratilova recently said she could challenge Steffi Graf's Open-era record of 22 Grand Slam titles. Williams is currently gunning for an 18th major to match Navratilova and Chris Evert.

Off-court, she is heavily involved in charity with two Serena Williams Secondary Schools in Kenya, and she also has her own clothing line.

But she said coaching could be an option. Several legends of the game have recently joined the coaching ranks, including Ivan Lendl, Boris Becker and Stefan Edberg.

"I never would say no to anything because I actually never thought I would play this long. So who knows, there's always apparently opportunities," Williams said, after moving into the third round of the Australian Open.

But she added: "I don't even know if I would be a good coach. We'd have to see."