Serena Williams is still unsure if she will defend her title at the Australian Open in just two weeks, despite saying her career isn’t done yet.

Williams lost in her return to tennis on Saturday, beaten by French Open champion Jelena Ostapenko in an exhibition match, 6-2 3-6 10-5.

Williams called it a “wonderful” match despite the defeat.

But the Australian Open – beginning in Melbourne on January 15 – is looming large.

“I don’t know if I am totally ready to come back on the tour yet,” Williams said.

“I know that when I come back I definitely want to be competing for championships. I am definitely looking forward to getting back out there.

“I am taking it one day at a time. I am going to assess everything with my team before deciding.”

The 36-year-old Williams took time off after winning the Australian Open last January while pregnant.

She gave birth to her first child, a girl named Alexis Olympia Ohanian Jr, on September 1.

Serena Williams cuddles newborn Alexis in September.

She married Reddit co-founder Alexis Ohanian in November.

Williams struggled with her serve in the 67-minute match at the Mubadala World Tennis Championship in Abu Dhabi.

“I don’t think I am going to rate my performance,” Williams said.

“I have plenty of comebacks, from injuries, from surgeries, but I’ve never had a comeback after actually giving birth to a human being.

So, in my eyes, I feel it was a wonderful, wonderful match for me.”

Williams insisted she has a lot more tennis to play.

“Knowing that I have won 23 Grand Slam titles and several other titles, I don’t think I have anything more left to prove,” she said.

“But I am not done yet.”

US Open runner-up Kevin Anderson defeated Spain’s Roberto Bautista Agut 6-4 7-6 in the men’s final.