Swiss teenager Belinda Bencic has practiced alongside 1997 U.S. Open champion Martina Hingis for years under the tutelage of her coach, Hingis’ mother, Melanie Molitor.

“Almost everything I know, I know from her,” Bencic says of Hingis, the former world No. 1.

But the 17-year-old’s third-round 6-1, 7-5 upset win Friday afternoon on Court 17 at Flushing Meadows over sixth-seeded German Angelique Kerber, 26, was all hers.

Bencic, appearing in her first U.S. Open, smacked a serve that topped out at 107 MPH, hit 23 winners to Kerber’s 18, and won the last five games of the match to advance to the second week of a Grand Slam for the first time in her young career.

Her third-round appearance at Wimbledon this year was her previous best, but Bencic said the hard court of the U.S. Open “suits my game.” In the fourth round, Bencic will face No. 9 seed Jelena Jankovic of Serbia, though the former No. 1 junior player was still flying high immediately after Friday’s upset victory.

“It’s amazing that after last year I played junior here, and this year I’m in the fourth round,” she said, beaming. “It’s incredible.”

SNAP CHAT

It’s not enough for some fans to sit only feet away from their heroes at the U.S. Open. Some need a picture to capture the memory, even if it means interrupting a match.

Jankovic, Bencic’s fourth-round opponent, was heckled Friday on two separate occasions during her third-round 6-1, 6-0 win over Sweden’s Johanna Larsson at Arthur Ashe Stadium. Strangely enough, it wasn’t a Larsson supporter trying to get Jankovic off her game, but rather a rabid fan seeking a private pose.

“There was a funny (fan) who was like, ‘Hey, turn around, I want a picture of you.’ I was walking,” Jankovic said. “And then another times after a couple of games he goes, again: ‘Hey, turn around, I need a picture.’ That’s basically it. But I didn’t tell anyone to (be quiet) … Some people were being loud up (in the upper deck) and moving. So that’s all.”

SOUTH JERZY

Poland’s Jerzy Janowicz has a short temper and has not advanced past the second round of the U.S. Open in three years after losing Friday, so no, the 43rd men’s seed did not hold back after a four-set defeat to 18th seed Kevin Anderson of South Africa.

“All the time something here,” said Janowicz, 23, who had lost in the first round in both 2012 and 2013 prior to Friday’s disappointment. “Either I have injury or I have worst day of career.”

Janowicz won the first set, which lasted 56 minutes, 7-6 with an 8-6 tiebreak. But when Anderson shifted momentum, the Polish player appeared to lose both his game and interest, and Janowicz won only six of the final 24 games as the next three sets lasted a total of just 91 minutes.

“I’m not so angry, because there’s nothing to do,” Janowicz said. “I have no explanation for what happened today. Completely drama today. Some days you don’t feel the racket, don’t feel the ball, can’t make simple shots. I don’t feel my game, or anything.”

QUICK WORK

No. 4 men’s seed David Ferrer had by far the easiest path to this year’s third round when the Spaniard’s scheduled second-round opponent, 67th seed Bernard Tomic of Australian, withdrew from the match due to a hip injury.

“I was sick for the last 10 days,” Tomic said. “It was difficult having the flu, but my hip’s a little bit not in shape. I’m feeling it inside. So I did the best thing not to play. You know, I don’t want to muck around with that area. For sure something is there. I’ve got to get it checked, got to get it analyzed the next few days. I’ve got to look into it and see what’s wrong, because I’m definitely feeling something in that area. For me, it’s not good right now. It’s painful.”

UPSET CITY

No. 39 women’s seed Peng Shuai of China upset fourth-seed Agnieszka Radwanska in straight sets in the second round, 6-3, 6-4, and then on Friday Shuai also took down the 30th seed, Roberta Vinci, 6-4, 6-3.

Shuai, who also is competing in doubles, has matched her career best at the U.S. Open by reaching the fourth round, which she did only once in 2011. The road will get no easier, as she has drawn 14th seed Lucie Safarova.

GREAT CAUSE

There are two Wounded Warrior ballpersons working this year through the USTA Foundation Military Initiative: Todd Reed, 53, and Chris Bustamente, 44.

Reed, who joined the U.S. Army’s 82nd Airborne Division at Ft. Bragg, N.C., in 1980, lost his right foot in 1991 when a landmine exploded underneath him in Northern Iraq and underwent about 20 surgeries to clean and close the bottom of his right leg. Bustamante, of Long Island, is a sergeant in the U.S Army who was deployed to Afghanistan and in 2012 sent back to Ft. Drum in New York for medical reasons.