Serena Williams has admitted she ''definitely'' wants another baby.

The 36-year-old tennis star welcomed her baby daughter Alexis Olympia - whom she has with her husband Alexis Ohanian - into the world in September last year, but she has insisted she would love to have another tot in the future, although she'd also like to focus on her tennis career.

She said: ''I definitely want two [kids], God willing. But right now, I want tennis as well. So, I'm going to wait and see what happens.

''It's definitely not easy. I have this undying drive to be the best that I can be. Whether it's [being] a mom or playing tennis or doing my designing. I just want to do the best that I can.''

Serena also admitted that her first five months of motherhood has been ''amazing'', as she says that being a parent comes ''naturally'' to her.

She added: ''It's been amazing. I've always wanted to be a mom but I never seemed to have time with my career. Then, it just happened, and I was like, 'I don't know.' I just dove right in.

''It's so natural for me. I love it. I love her so much. We have a great little family going on.''

But the tennis superstar insists that it can be difficult being a working mother, especially when her husband Alexis - who is the co-founder of website Reddit - is also often busy.

She said: ''Working motherhood is real. It's so real. But I have my priorities and Olympia is that. And Alexis [co-founder of Reddit] works all the time as well. He's not even here right now, he's working on his new VC fund. So, that's great! But I'm never a day without Olympia. She's my priority and everyday I need to be home with her. I don't wanna miss any moments with her.''

Right now, nothing makes Serena happier than seeing her tot's toothless grin.

When asked by 'Entertainment Tonight' what Olympia's most precious moment has been, Serena gushed: ''Her toothless smile. She's so happy. That is my favourite thing, her toothless smile.''