KEY BISCAYNE, Fla. (AP) — Trailing in the first set of her first match at the Sony Open, Serena Williams grunted with every shot and screamed with every point she won.
And then, on the pivotal point, she didn't make a sound — or take a swing.
Williams capitalized on a critical double-fault Thursday by Yaroslava Shvedova to survive a 69-minute first set and win, 7-6 (7), 6-2.
"It was an incredibly tough first set," Williams said. "I just needed to relax and yet keep up the intensity."
The top-ranked Williams seeks a record seventh Key Biscayne title, and her second in a row.
No. 4-seeded Maria Sharapova, a five-time runner-up in the tournament, joined Williams in the third round by beating Kurumi Nara 6-3, 6-4. Seeded players had first-round byes.
On the men's side, Lleyton Hewitt became the third active man to win 600 matches when he rallied past Robin Haase 3-6, 6-3, 6-3.
Fellow Australian Bernard Tomic lasted only 28 minutes in the shortest match since the ATP started keeping such records in 1991. Tomic, mounting a comeback from surgery on both hips and playing for the first time since January, won just 13 points and lost to Jarkko Nieminen 6-0, 6-1.
"I did the best as I could," Tomic said. "Hopefully in a little bit of time I can get back to 100 percent."
Americans Jack Sock, Ryan Harrison, Sam Querrey and Donald Young won first-round matches.
Williams, who owns a small share of the Miami Dolphins, wore a dress in the team's orange and turquoise colors — which may explain her slow start. Or maybe it was because she hadn't played since Feb. 21.
Williams had to erase a 5-3 deficit in the first set, and then fell behind 6-3 in the tiebreaker. Shvedova pushed a forehand into the net, then hit a nervous double-fault that allowed Williams to exhale.