Eight-time champion Serena Williams won her opening match Friday at the new site of the Miami Open by beating Rebecca Peterson 6-3, 1-6, 6-1.

Williams played poorly for a stretch and was broken three times but steadied her game in the final set to pull away. She avoided a repeat of last year, when she was eliminated in her first match by Naomi Osaka.

The No. 1-ranked Osaka beat qualifier Yanina Wickmayer 6-0, 6-7 (3), 6-1. Osaka hit 14 aces and overcame a ragged stretch in the second set, when she became so frustrated she threw her racket.

"I had a bit of a dip," Osaka said. "It was really hard for me, I think, emotionally in the second set, because I just started thinking about winning, not exactly the things I could do in order to win."

The tournament moved this year from Key Biscayne to the Miami Dolphins' stadium complex, and Williams and Osaka took part in the ribbon-cutting ceremony Wednesday.

Both found the mix of sun and shadows in the cavernous stadium a challenge. Williams struggled to see the ball on at least a couple of points, shielding her face with her left hand as she approached shots.

Osaka confirmed the sun was an issue against Wickmayer in the unfamiliar setting.

"It's a little bit tricky to get used to it," Osaka said. "I think for me it got better as time went on. I found comfort in knowing she also was in the same conditions. It's not something that I should really be complaining about."

Defending men's champion John Isner hit 20 aces, lost only 11 points on his serve and beat qualifier Lorenzo Sonego 7-6 (2), 7-6 (7).

No. 5-seeded Kei Nishikori was upset by Dusan Lajovic 2-6, 6-2, 6-3. Lajovic improved to 3-14 against top-10 players.

No. 16 Gael Monfils, who has been hampered by an Achilles injury, withdrew before his opening match.

In other women's play, Canadian 18-year-old Bianca Andreescu, who overcame a match point to win her opening match, reached the third round by beating No. 32 Sofia Kenin 6-3, 6-3. Andreescu won her first career title last week at Indian Wells.

Three-time champion Venus Williams overcame a wobbly start to beat No. 24 Carla Suarez Navarro 7-6 (4), 6-1.