Serena Williams played her first main-draw match since winning the 2017 Australian Open and came out on top at the Indian Wells Masters on Thursday.
Williams spent time away from the court during her pregnancy and following the birth of her daughter Alexis Olympia in September, but the former world number one made her long-awaited return as she defeated Zarina Diyas.
Fellow mother and 2016 Indian Wells champion Victoria Azarenka also progressed in straight sets as she made her own season bow, seeing off British number two Heather Watson late in the day.
American teenager Cici Bellis set up a second-round meeting with defending champion Elena Vesnina.
Serena in command
Williams, a 23-time grand slam singles champion, showcased her power and groundstrokes to see off Diyas 7-5 6-3.
Williams edged a difficult opening set, which remained on serve until the 11th game, when the 36-year-old moved ahead, much to the delight of the crowd.
While breaks were at premium in the first set, it was a completely different story in the second following five consecutive breaks of serve.
"It was incredible," Williams said during her on-court interview. "It's been over a year and a kid later - and I get to go home now to her!
"It definitely wasn't easy. I've played [Diyas] several times before and we always have a couple of tight sets. I'm a little rusty, but it doesn't matter. I'm just out here on this journey doing the best I can."
Azarenka back in the swing of things
A custody battle has kept Azarenka from the Tour since Wimbledon, meaning that she, like Serena, was making her return on Thursday.
And the Belarusian, like Williams, earned a first-round win, defeating Watson 6-4 6-2 in a hard-fought match that included one 18-minute game.
Having been welcomed back by the Californian crowd, Azarenka was full of emotion in her on-court interview.
"It truly means the world to me to just be able to be here, to play, to enjoy myself and do what I love to do," she said. "Walking out on court, I felt so much love. I almost had tears in my eyes. It's an amazing feeling to be back playing and having fun."
Bellis belies her age
The American is the youngest player in the top 40 at the age of 18 but Bellis continues to make waves on the WTA Tour.
She eased past Sara Sorribes Tormo 6-0 6-3 to earn a showdown with titleholder Vesnina, the 24th seed.
Only 65 minutes were needed for Bellis to close out proceedings against her Spanish opponent.
Olympic gold medallist Monica Puig, meanwhile, rallied from 4-0 down in the second set to prevail 6-3 7-6 (7-3) against Beatriz Haddad Maia.
Ekaterina Makarova and Yanina Wickmayer also progressed, but Acapulco champion Lesia Tsurenko lost.