The 23-time major winner defeated Zarina Diyas of Kazakhstan 7-5, 6-3 in the first round Thursday night.

"It was incredible,'' Williams said on court after the 1½-hour match. "It's been over a year and a kid later and I get to go home to her now, and I'm excited about that.''

With husband and Reddit co-founder Alexis Ohanian looking on, Williams played from behind until breaking Diyas in the 11th game.

Williams served a love game capped by a 100 mph ace in her first service game. She had break points in the first and fifth games but couldn't convert. She started hitting harder and her familiar grunting returned when she tied the set 5-all.

Diyas and Williams traded service breaks early in the second set. Williams then broke her opponent again en route to winning the final five games. She smiled as she walked to the net, and her family gave her a standing ovation.

"It definitely wasn't easy,'' Williams said on court. "We always have a couple tight sets. It was good. I'm a little rusty, but it doesn't matter. I'm just out here on this journey and doing the best I can.''

Also in Williams' box were her mother Oracene, sisters Lyndrea and Isha, her agent, and her coach Patrick Mouratoglou. Older sister Venus watched from a balcony seat in an upper-level box on a 68-degree night in the Southern California desert.

Williams has been away since winning the 2017 Australian Open early in her pregnancy. She gave birth to daughter Alexis Olympia Ohanian Jr. six months ago.

Ohanian bought four billboards along Interstate 10 outside Palm Springs in tribute to his wife. The fourth billboard shows a photo of Williams and their daughter with the phrase "G.M.O.A.T'' -- greatest mother of all time -- and is signed by Alexis Sr. and Jr.

Williams' only competitive appearances since the birth came in December at an exhibition in Abu Dhabi, a Fed Cup doubles match with sister Venus last month and an exhibition in New York on Monday.

She is playing at Indian Wells under a protected ranking of 22nd. Williams hasn't been unseeded at a tournament since 2011 in Cincinnati.

It was pointed out to Williams that it was International Women's Day.

"I'm so excited to play on this night,'' she said. "It was meant to be I think. I'm really happy about that.''

Another new mother, Victoria Azarenka of Belarus, followed Williams on the stadium court. The two-time winner of the desert tournament needed a wild card to get in because she has been off the tour since Wimbledon. Azarenka, who gave birth to son Leo in December 2016, has been in a custody fight that limited her travel. She was to play Heather Watson of Britain.

In other first-round matches, CiCi Bellis overpowered qualifier Sara Sorribes Tormo 6-0, 6-3.

The 18-year-old American, who turned down a full scholarship from Stanford to turn pro last August, had her serve broken just once by the Spaniard in the 65-minute match. Bellis earned a second-round matchup with defending champion Elena Vesnina of Russia.

Bellis led five Americans into the second round. She was joined by wild card Danielle Collins and Jennifer Brady, who both were stretched to three sets. Taylor Fritz needed three sets to advance in the men's draw, as did Mitchell Krueger and Jared Donaldson.

Other winners Thursday were Olympic gold medalist Monica Puig of Puerto Rico, qualifier Yanina Wickmayer of Belgium and Fernando Verdasco of Spain.