On Monday, CiCi Bellis picked on someone her age. The U.S. Open's 15-year-old marvel, whose main-draw upset of Australian Open finalist Dominika Cibulkova caused a major stir last week, pounded 16-year-old Renata Zarazua of Mexico, 6-1, 6-3.

It was Bellis' first match in the girls junior competition after her conspicuous debut on the biggest tennis stage, creating a lavish follow-up fuss for her second-round loss.

Logically, Monday was a significant step back from the earlier hullabaloo. Though assigned to the Open's No. 3 show court, Bellis played before a mostly empty Grandstand of about 1,000 spectators -- nothing close to the 2,800 who packed into Court 17 for her second main-draw match, while several thousand more watched on the grounds' huge video screens.

But life has changed for Bellis, the home-schooled kid from Atherton, California, already being hailed as the future of American tennis.

"A lot of social media," she said. "I think, on Twitter, I'm up to almost 8,000 followers. I had 300 before. And on Instagram I've got, like, 3,000 more, almost 4,000. I had 1,200 before."

And there was a telephone call of support from a retired four-time major-tournament champion.

"Before I played my second-round match," Bellis said, "Kim Clijsters called me. She's been, obviously, my favorite player of all time. She called me and she was, like, 'Hi, CiCi, this is Kim Clijsters; I don't know if you've heard of me before.'

"So funny. Yeah, that was amazing."

Bellis has signed a lot of autographs in recent days. "I just do, like, 'CB.' I wouldn't be able to write my whole name."

Also, "I've had people even on the street come up and ask, 'Are you CiCi Bellis?' And it's kind of weird. I love it, though. It's amazing.

"I love competing in this tournament. I love being the first seed [in juniors]. When you're kind of a target, I play better that way. I don't feel any pressure. I feel more confident in a way."

Besides, in the juniors, she's only three years under the age limit.