NEW YORK, NY, USA -- CoCo Vandeweghe became the third American so far to reach the 2017 US Open quarterfinals, when the No.20 seed defeated Lucie Safarova of the Czech Republic, 6-4, 7-6(2), on Arthur Ashe Stadium on Monday afternoon.

Vandeweghe follows compatriots Venus Williams and Sloane Stephens into the quarterfinals after winning the 100-minute match. Safarova was unable to join her countrywomen Karolina Pliskova and Petra Kvitova in the final eight, as the tournament is turning out to be excellent for both the United States and the Czech Republic.

"I think it's great to have three, maybe hopefully four tonight, Americans in our American Grand Slam," said Vandeweghe in her press conference after the match.

Vandeweghe thus prolongs her strong year, which includes a semifinal appearance at the Australian Open, her second career quarterfinal at Wimbledon, and a run to the final of the Bank of the West Classic in Stanford last month. This is the first US Open quarterfinal of her career.

After Vandeweghe won her first encounter with Safarova in the fourth round of Wimbledon in 2015, the Czech had won their last three meetings, including a three-set dust-up at the BNP Paribas Open in Indian Wells earlier this year. But the California native turned the tables today.

Vandeweghe started the contest shaky on serve. She survived break points at 1-1 and 2-2, as she had a couple double faults and a first serve percentage hovering around 50 percent. Safarova, however, was often unable to get an accurate handle on her return -- a problem that would linger throughout the match.

Vandeweghe had to fend off another break point at 4-4, after hitting three unforced errors off the backhand side in the game. But Safarova hit a backhand error of her own to miss her chance, and the set progressed to 5-4.

Safarova rued the failures to convert on Vandeweghe’s serve in the next game, when the American's powerful hitting allowed her to obtain her first break points of the match, which were also set points. She dutifully converted her second set point when Safarova could not successfully put a Vandeweghe forehand back in play.

The players had similar stats in the first set, as Vandeweghe had seven winners to 10 unforced errors, compared to Safarova’s seven and 12 respectively. But Vandeweghe overcame a low first service percentage by winning an incredible 68 percent of her second serve points.

The second set was even more closely contested. Safarova, the former World No.5, saved a break point to hold for 2-2, and then achieved her first break of the match, when the American hit a forehand error down break point to hand over a 3-2 lead.

Any momentum Safarova may have had was short-lived, though, when solid returning by Vandeweghe let her break back to level the set at 3-3. Both players were smooth on serve for the rest of the set, and there were no more break points for either combatant up to the tiebreak.

Vandeweghe demonstrated steely composure and raised her game to cruise through the tiebreak. Safarova missed a volley after she could not handle a powerful Vandeweghe groundstroke, giving the American a 4-2 lead. Vandeweghe would not cede that advantage, winning the next three points, with an ace on match point to clinch victory.

"I knew in the stickier points of the second set where it was getting tight that I had to show her that I was going to hustle down a few more extra balls," Vandeweghe said. "I was going to be present inside the court for her short balls and not let her dictate, but she did a good job holding serve at 5-4 and at 6-5. She was hitting her spots very well. She did that a lot throughout her whole match."

It was a clean match, with neither player having a disproportionate amount of unforced errors to winners, and six aces for both. One break decided the match, so Safarova will be displeased with her 1-for-5 conversion rate on break points, and only winning 30 percent of points on her second serve.

Vandeweghe, by contrast, won the big points when it mattered, emerging victorious on 67 percent of her service points, and converting two of her four break points.

Vandeweghe moves on to an intriguing encounter against another Czech, World No.1 Karolina Pliskova, in the quarterfinals. The American leads the head-to-head by two matches to one.

"It's definitely the first strike kind of tennis, I think is the easiest way to simplify it," noted Vandeweghe about the upcoming quarterfinal against Pliskova. "If I'm hitting my shots, I'm definitely doing a lot better job in the scoreline than she is and vice versa. So I think it's pretty much as simple as that."