Two-time Indian Wells champion Victoria Azarenka shook off a slow start to beat Vera Lapko 6-2, 6-3 on Wednesday and set up a second-round meeting with long-time rival Serena Williams.
Azarenka, a former world number one now ranked 48th in the world, said she started a little too passive in dropping the first two games against her fellow Belarusian but roared back to seal the win with ease.
She was looking forward to taking on 10th-seeded Williams, who like all the seeds in the combined WTA and ATP Masters event has a first-round bye.
The American has won 17 of their 21 prior encounters, but Azarenka won their most recent clash -- in the 2016 Indian Wells final.
"Of course it's going to be a very special match for us," she said of their first clash since both became mothers.
"We have such a big history, it's going to be really special. She motivates me, she inspires me, she pushes me to be better," Azarenka said of Williams.
The opening day of women's main draw play saw highly touted teenagers Bianca Andreescu and Amanda Ansimova reached the second round.
Canada's Andreescu, 18, rallied from a set down to beat Romanian Irina-Camelia Begu 6-7 (3/7), 6-3, 6-3.
"For me, the ending is the most important, so I'm really glad I pulled through," said Andreescu, who has won 22 matches this season including qualifying and main draw.
She has climbed steadily in the rankings, rising from 107th to start the year to 60th.
"Mentally... I was like, I might as well go for my shots, and see where that leads me and that's what I did, and it worked," said Andreescu, who booked a second-round meeting with 32nd seed Dominika Cibulkova.
American Ansimova, 17, lined up a meeting with 16th-seeded Elise Mertens of Belgium with a 6-0, 6-4 victory over Serbian Aleksandra Krunic.
Third-seeded Petra Kvitova, who will face either Venus Williams or Andrea Petkovic in the second round, said she wasn't surprised to see teenagers making such a strong showing.
Elsewhere, American Sofia Kenin didn't have to wait long to avenge her loss to Wang Yafan in last Saturday's Acapulco women's final -- ousting China's Wang 1-6, 7-5, 6-4.