Serena Williams, saying she felt nervous and rusty, made a triumphant WTA return from a left ankle injury, defeating China's Zhang Shuai 6-2, 6-3 at the WTA and ATP Miami hardcourt event.
Fellow former World No. 1 players Kim Clijsters, Maria Sharapova and Caroline Wozniacki also on Thursday advanced to the third round at the $9.6 million tournament, which awarded byes in the first round to seeded players.
In her first tournament match since losing in the fourth round at the Australian Open, Williams fired six aces and connected on 64 percent of her first serves while dropping only one service break to advance in 80 minutes.
"I was a little bit rusty and a little bit nervous too," Williams said. "I haven't played here for so long and I wanted to do well. So I was really nervous out there, but I think now I've gotten one under I'll be better."
The 13-time Grand Slam singles champion advanced to a third-round match against Italy's Roberta Vinci, who ousted Bulgarian Tsvetana Pironkova 7-5, 6-1.
Tenth seed Williams, a five-time winner at Miami, missed the event the past two years because of illness and injury.
"I'm always a little nervous in the first round. I kind of chill out after that," Williams said. "Last time I played I played horrible and I was thinking as long as I don't hit a ball into the stands I'll be good.
"I didn't do that today, so it worked out well for me."
Former World No. 1 Williams played for the US Fed Cup team last month, winning two singles matches in a 5-0 World Group II victory over Belarus.
But she had not been in a tour match since losing to Russia's Ekaterina Makarova in the round of 16 at Melbourne. Williams withdrew before her Brisbane quarter-final with a sore ankle in her only other WTA start this year.
Williams won a day after her sister, seven-time Grand Slam champion Venus Williams, beat Japan's Kimiko Date-Krumm 6-0, 6-3 in a first-round match.
It was the first WTA event for Venus since she pulled out of last year's US Open with the auto-immune disorder Sjogren Syndrome, which saps her energy and causes pain in her joints.
"It was amazing. I was so happy for her," Serena Williams said of Venus. "She has been through so much and to know you can go through that and continue to play and never give up gave me hope and inspiration.
"I felt like at some points I would give up and she never did. Venus just really inspires me. And not just in tennis but in life in general."
Williams, 46-0 in first-round matches at Grand Slams, improved to 12-0 in Miami openers but praised Chinese wildcard Zhang, saying, "I think she played really well. She's pretty young. She's doing really well."
Russian second seed Sharapova advanced by rallying to defeat Israel's Shahar Peer 4-6, 6-3, 6-3, after two hours and 24 minutes. She denied Peer on 10-of-13 break-point chances while taking half the 10 she earned for herself.
World No. 2 Sharapova lost to top seed and World No. 1 Victoria Azarenka of Belarus in the Indian Wells final last Sunday in her most recent prior match.
Three-time Grand Slam singles champion Sharapova will next face American Sloane Stephens, who ousted Italy's Sara Errani.
Belgium's Clijsters ousted German 14th seed Julia Goerges 6-2, 7-5. The second set saw nine service breaks.
"I don't think there's anybody who plays a whole tournament with perfect tennis, so you have to try and battle through, and find the solutions when you're not playing your best," Clijsters said.
Danish fourth seed Wozniacki opened by ousting Czech Barbora Zahlavova Strycova 6-4, 6-0.
On the men's side, US wildcard Ryan Harrison ousting Italy's Potito Starace 6-7 (6/8), 6-4, 6-4 to book a second-round date with Swiss star Roger Federer, who has won his past three tournaments in a row including last week's title at Indian Wells.
Marcus Baghdatis of Cyprus advanced with a 6-1, 6-1 triumph over Argentina's Leonardo Mayer, advancing to a second-round match on Saturday against Serbian World No. 1 Novak Djokovic, winner of the past three Grand Slam crowns.