Serena Williams says she never considered calling time on her tennis career as she aims to enjoy playing without pressure at Indian Wells.

The 23-time grand slam singles champion beat Zarina Diyas 7-5 6-3 in the opening round on Thursday, making her first WTA Tour appearance since she won the 2017 Australian Open while two months pregnant.

And Williams was always determined to come back to the court following the birth of her daughter Alexis Olympia in September, even if she is still easing her way back into action in California.

"I surprised myself with some of the errors but right now, for this particular tournament, I'm really just trying to take it easy and not put so much pressure or stress or expectation on myself," she told a post-match news conference.

"I feel like it's one of the few times I've been able to do that. I went in there knowing I'm not going to be my best these first few matches, but I'm playing with nothing to lose. I have everything to gain.

"I'm playing with real joy out there. No matter what happens I know I'm capable of being strong in my life.

"I felt like my story [on the court] wasn't over. It [retirement] wasn't even a question for me."

Serena could face her sister Venus in the third round, should both players come through their next matches.