Seven-time champion Serena Williams needed only 41 minutes to beat 15-year-old American CiCi Bellis 6-1 6-1 on Sunday in the third round of the Miami Open.

Bellis made headlines by winning a match at last year’s US Open, but she couldn’t stay with the world No.1.

Williams won 51 of the 65 points and lost only two points in seven service games.

“It wasn’t like, ‘Oh, I’m so happy to win this match,”‘ Williams said. “It was tough. She’s young and her being an American, you want to see people like her do well.”

Williams’ opponent in the round of 16 will be 2006 champion and 24-seeded Svetlana Kuznetsova, who beat No. 13 Angelique Kerber 6-3 3-6 6-3.

Williams withdrew before the semi-finals at Indian Wells last week, citing an ailing right knee, but hardly had to run against Bellis. Williams hit 13 winners to only one by the teenager, who is the world’s top-ranked junior and still an amateur.

“I was pretty nervous,” Bellis said.

“I mean, she’s No.1 in the world and like the best of all time for a reason. I think it was just a really good experience for me for the future and I’m glad I got to do it, but she’s a lot better than me for right now.”

Simona Halep, who won Indian Wells a week ago, reached the women’s fourth round by beating No.30 Camila Giorgi 6-4 7-5.

Two-time champion Victoria Azarenka lost to Flavia Pennetta 7-6 (7-5) 7-6 (7-6).