U.S. Open Day 6 recap: Krunic shows No. 3 seed Kvitova the door in upset

NEW YORK -- Serena Williams battled, Novak Djokovic cruised and Petra Kvitova was shown the door on Day 6 of the U.S. Open. Meanwhile, two-time finalist Victoria Azarenka is quietly building a head of steam as the second week approaches. 

What happened

Another one bites the dust as No. 3 seed Petra Kvitova stunned: The first time I remember ever seeing Aleksandra Krunic, she was a tiny 14-year-old at a Serbian Fed Cup that was highlighted by Ana Ivanovic and Jelena Jankovic. Yet even with those two stars on the team, Krunic's personality and feistiness were memorable. She wasn't wowed by her Fed Cup teammates or by the occasion, and would even jump in to field questions ahead of her elders. But that was six years ago and Krunic hasn't done much since. Until this year when she came into the tournament ranked No. 145 and qualified for her first U.S. Open main draw and has proceeded to go giant-killing. She upset 27th-seed Madison Keys in the second round in three sets and now she knocked out Wimbledon champion Kvitova in straight sets, 6-4, 6-4. Krunic is listed at just 5-foot-4  but she possesses a serve that can come in at 115 mph. Against Kvitova she used her scrambling defense to frustrate the powerful Czech, who could never find her rhythm off the ground. 

"I still cannot believe I won against Madison, and now I won against Petra," Krunic said. "It's like so many things happening in my mind that I'm trying to -- I cannot say I'm trying to stay on the ground, because I don't think it's ever going to happen to me that I'm going to change or whatever. But I'm trying to believe it, but then like, okay, when I believe it I'm afraid that I'm going to have so much emotions. So I'm trying to keep it all together." With her run to the fourth round, Krunic has nearly matched her career earnings this week, taking home a check of at least $187,000. She'll play defending finalist Victoria Azarenka, who lost just two games to Elena Vesnina in her third round match. Until then, Krunic will just have to keep bullying the No. 1 player in the world around in the gym. "I kicked out Djoko (Novak Djokovic) from the quiet room in the gym before my match with Madison, and today before my match I also saw him in the gym," Krunic said. "We were kind of joking after the match. He said, 'Keep kicking me out if you're playing good.'"​

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As for Kvitova, what can we say. Her New York jinx continues. She's never made it past the fourth round here despite winning lead-up tournaments and rounding into form. She looked great in her first two rounds but couldn't find a way to hit through Krunic today. It's disappointing, but it's also par for the course. 

Serena and Novak move into the fourth round: Serena Williams was made to fight hard for a 6-3, 6-3 win over Varvara Lepchenko, while Djokovic looked sharp in his 6-3, 6-2, 6-2 win over Sam Querrey. The Serb built a 5-0 lead in just 15 minutes. 

Milos Raonic and Kei Nishikori on a collision course: Victor Estrella Burgos' U.S. Open debut is over, losing 7-6 (5), 7-6 (5) 7-6 (3) to Raonic. It was a more than respectable effort from Burgos, who came within a forehand here and there of stealing a set from the Canadian. Raonic has lost just one set in three matches and he won every tiebreak he played in the first week, going 6-0. He'll go up against 10th-seed Nishikori, who has rolled through the first three rounds. He has not lost a set and here's how the eight sets he's played went: 6-2, 6-4, 6-2, 6-4, 6-1, 6-4, 6-2, 6-3. He's breaking his opponents with ease -- he broke 25th-seed Leonardo Mayer six times Saturday -- and he's minimizing the amount of time spent on court. All good things leading up to what should be a great encounter with Raonic. 

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​Kaia Kanepi does what she does at the Slams: Kanepi is the Loch Ness Monster of the WTA. We have no idea where she is during the regular season but when the majors roll around you get an occasional, fleeting glimpse of what she could accomplish if she remained injury free and committed throughout the year. The talented but frustratingly erratic Estonian bageled 15th-seed Carla Suarez Navarro 7-5, 6-0 to advance to the fourth round, where she'll play Serena. 

No American men in the second week: For the second straight year, there will be no American men in the fourth round. John Isner was foiled for the third straight U.S. Open by Philipp Kohlschreiber, losing to the German 7-6 (4), 4-6, 7-6 (2), 7-6 (4). As a result, Isner has failed to make it past the third round at 10 of the last 11 Slams he's played. The last time an American man played a fourth-round match at the U.S. Open was in 2012. It was Andy Roddick's last match of his career. Symbolic. 

Tommy Robredo schools Nick Kyrgios: Kyrgios' debut on Ashe started off like a lightning bolt. In the blink of an eye, behind monstrous serving and blistering shot-making, the 19-year-old raced to a 5-0 lead. He was loving it so much he sat down at the changeover and started bopping his head and singing along to "Blurred Lines". Was this game of tennis really that easy? No. Slowly and methodically the Spanish veteran reeled him back in. Kyrgios' loss of concentration cost him and he started to misfire. His lack of discipline, which can produce some audacious shot-making, became his undoing. Robredo may have dropped the first set but he began to unleash his variety of spins and placement to keep Kyrgios off-balance. By the fourth set Robredo had successfully transformed the match into a chess game, and that's something Kyrgios isn't ready to handle quite yet. He gave Kyrgios nothing, hitting no unforced errors in the second set and minimizing them for the rest of the match. The best example of Robredo's merciless and measured game: with Kyrgios cramping badly in the final games, Robredo opted to challenge a ball that was clearly out just to make Kyrgios stand there and cramp some more. Robredo won 3-6 6-3 7-6 (4) 6-3. He'll play Stan Wawrinka, who got a walkover into the fourth round. 

Another Bouchard battle: In swirling conditions, the seventh seed found a way to win in her second-straight three setter, beating BarboraZahlavovaStrycova,6-2, 6-7, 6-4​. She'll gain confidence knowing she doesn't have to play her best to win. She gets 17th seed EkaterinaMakarova next. 

Photo of the day

Julian Finney/Getty Images

Quote of the day

Q. You said you were watching the Wimbledon final. Were you rooting for Petra or Bouchard?

ALEKSANDRA KRUNIC: Petra. I like Petra a lot as a person. She's very down-to-earth and I respect her a lot. I like when I can say hi and talk to the players that are much higher ranked than me and I don't feel such a difference in our levels. Because still we're all human beings, you know, and that someone is doing a better job in tennis than me doesn't mean we're not on the same level as people, you know, as personal.

Video of the day

Novak Djokovic ends his press conference with a song: 

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