CiCi Bellis, 15, stuns Cibulkova at US Open

Ah, yes, the joys of raising kids. And make no mistake, Bellis is a kid. She is home-schooled and about to start 10th grade.

Her first memory of the US Open is watching on TV while Maria Sharapova played. She likes to hang out at the mall with friends back home in California. Asked whether she’s a fan of pop star Justin Bieber, Bellis answered, ‘‘I used to like him when I was younger, a couple years ago.’’

Her victory was part of a 9-4 showing by American women Tuesday, including 8-0 against unseeded opponents. In an all-American match at night, another teen, Taylor Townsend, lost quickly to two-time defending champion Serena Williams, 6-3, 6-1.

‘‘We have such an amazing future,’’ Williams said about US women’s tennis. ‘‘We have so much to look forward to.’’

Williams’s win came after Roger Federer beat Marinko Matosevic, 6-3, 6-4, 7-6 (7-4) with Michael Jordan sitting in Federer’s guest box in Arthur Ashe Stadium.

‘‘Growing up, he was my big sporting idol,’’ Federer said. ‘‘Having him here is unbelievably special.’’

Aside from the Williams sisters, American tennis fans have not had much reason to cheer for their own in the latter stages of major tournaments in recent years. That’s why the occasional run by a young US player — think Melanie Oudin, wearing ‘‘Believe’’ on her sneakers in 2009 — stirs interest at Flushing Meadows.

‘‘Believing was the No. 1 thing that I had to do today,’’ said Bellis, whose nickname CiCi is derived from the initials of her first and middle names, Catherine Cartan.

Bellis plans on playing in the US Open junior tournament. She lost in the third round of that event last year; she lost in the first round of the Wimbledon juniors last month.

But Tuesday, there she was in front of a supportive, overflowing crowd on Court 6 at Flushing Meadows, taking it to Cibulkova, the Australian Open runner-up.

‘‘I went into the match thinking it was going to be such a great experience,’’ said Bellis, whose rapid-fire sentences tend to finish with a gurgle of laughter, ‘‘but I never thought I would come out on top winning.’’

Neither did her parents. Her mother, Lori, wasn’t there because she gets too nervous watching in person, Gordon Bellis said. So Lori stayed at their hotel, getting updates via text from Gordon.

‘‘She asked how bad it was going in the first set. And so I told her [CiCi] actually won the first set. She couldn’t believe that,’’ Gordon said. ‘‘We were just thankful that she didn’t get double-bageled.’’

After trailing 3-1 in the third set — ‘‘kind of a bummer,’’ Bellis would say later — she came back to even things, and then broke the 25-year-old Cibulkova in the final game. When it ended, Bellis crouched at the baseline and pumped her fists, then ran over to the stands for congratulatory hugs.

‘‘I didn’t expect her to play so aggressive today. I thought she’s kind of a player who’s just putting the ball back and running around,’’ Cibulkova said. ‘‘That didn’t happen today. She was really aggressive on the court and that maybe surprised me in the first set.’’

Bellis was making her main-draw tour-level debut, having earned a wild-card invitation from the US Tennis Association by winning the USTA Girls’ 18s National Championship, the youngest to do since Lindsay Davenport also won it at 15 in 1991.

Not since Anna Kournikova was 15 in 1996 had someone so young won a match at the US Open. And not since Mary Joe Fernandez was that age in 1986 had an American done it.

Next up for Bellis is a second-round match against 48th-ranked Zarina Diyas of Kazakhstan. And Gordon Bellis said Lori might decide to attend that one. No word on what sort of rules Mom will have to follow.

Wimbledon champ Petra Kvitova fared far better than the last time she came to New York after winning at the All England Club. In 2011, she lost in the first round; on Tuesday, she beat Kristina Mladenovic, 6-1, 6-0.

The player Kvitova defeated in the Wimbledon final, Eugenie Bouchard, was back to her winning ways in her return to the Grand Slam stage.

The seventh-seeded Bouchard routed Olga Govortsova, 6-2, 6-1. The last time she played at a major tournament, the 20-year-old made history: the first Canadian to reach a Grand Slam final.

In the Wimbledon title match, though, she was swept away by Kvitova, 6-3, 6-0, and things didn’t go much better in her three hard-court tuneups for the US Open. Bouchard won just one of her four matches, including an upset loss in her opener in her home tournament in Montreal.

But against the 117th-ranked Govortsova, she had little trouble. Govortsova, who has been ranked as high as 35th, had won just two main draw WTA matches this year.

Samantha Stosur, the 2011 US Open champ, also quickly dispatched a young American, beating Lauren Davis, 6-1, 6-4. Davis fell to 0-3 at her home Grand Slam event.

Svetlana Kuznetsova lost her first-round US Open match for the first time since 2005, the year she was the tournament’s defending champion. Kuznetsova, seeded 20th this time, was beaten 3-6, 6-2, 7-6 (7-3) by 82d-ranked Marina Erakovic of New Zealand.

‘‘It’s disappointing, it’s shocking, to lose first round,’’ said Kuznetsova, who won a hardcourt tuneup tournament in Washington this month.

‘‘I was not moving my feet, was not doing anything. And then, of course, she [started] to believe. In the end, it was just horrible.’’

The 29-year-old Russian is a two-time major champion: She won titles at Flushing Meadows in 2004 and at the French Open in 2009. Erakovic, meanwhile, has never been past the third round at a Grand Slam event and was 0-4 at the US Open until Tuesday.

Kuznetsova was asked whether this year’s tournament was special to her, because it is the 10th anniversary of her title in New York.

‘‘I didn’t care,’’ she replied. ‘‘It’s one more US Open.’’

John Isner, a former top American college player, beat this year’s top American college player in the first round.

The 13th-seeded Isner defeated Marcos Giron, 7-6 (7-5), 6-2, 7-6 (7-2). Giron earned his first spot in a Grand Slam tournament when he won the NCAA title for UCLA in May.

The big-serving Isner didn’t face a break point. He has shown that a player can compete in college then succeed in the pros after a successful career at Georgia from 2004-07. He’s the only American man currently ranked in the top 40 in the world. Giron, 21, announced in July he was turning pro after his junior season.

Fellow American Sam Querrey improved to 3-9 in five-set matches with a 6-2, 4-6, 6-4, 4-6, 6-3 victory over Argentina’s Maximo Gonzalez.

Victor Estrella of the Dominican Republic earned his first Grand Slam victory at age 34, beating Igor Sijsling, 2-6, 6-4, 6-3, 6-2. Estrella hadn’t played in a major tournament until this year.