NEW YORK (AP) — The Latest on the U.S. Open tennis tournament (all times local):
CoCo Vandeweghe double-faulted 12 times and is gone in the first round of the U.S. Open a year after making it all the way to the semifinals.
The 24th-seeded American lost to Kirsten Flipkens of Belgium 6-3, 7-6 (3).
Vandeweghe made a total of 35 unforced errors, 16 more than Flipkens.
At the 2017 U.S. Open, Vandweghe was one of four Americans in the semifinals.
Australian Open champion Caroline Wozniacki easily reached the U.S. Open’s second round by beating 2011 titlist Sam Stosur 6-3, 6-2.
The No. 2 Wozniacki is the highest-seeded woman left in the field after No. 1 Simona Halep lost her opening match.
Wozniacki was the runner-up at Flushing Meadows in 2009 and 2014.
Facing dangerously high temperatures expected to last for more than a day, the U.S. Open has extended a heat rule to men that only exists in the women’s tour.
The U.S. Tennis Association says its medical team recommended the immediate implementation of the heat policy for the men, who will be allowed a 10-minute break between the third and fourth sets.
Its statement says the tournament referee, along with the medical team, would continue to monitor conditions on site to determine when the extreme heat policy would no longer be in effect.
The WTA has a heat rule allowing women a break between the second and third sets. There is no such rule on the ATP Tour.
Temperatures were already in the mid-90s by the early afternoon and expected to stay there or above until late Wednesday.
The WTA’s heat rule is in effect at the U.S. Open, allowing female players a break between the second and third sets.
Players left the court on Louis Armstrong Stadium, where No. 10 seed Jelena Ostapenko and Andrea Petkovic split the first two sets.
The heat rule allows for a 10-minute break if either player requests it. If both decline, play continues.
The ATP Tour does not have such a rule for the male players.
It was already 95 degrees (35 Celsius) when No. 24 seed Coco Vandeweghe took Court 17 for her match following No. 5 seed Petra Kvitova’s victory. Kvitova and Yanina Wickmayer wore towels around their necks during changeovers to battle the heat.
Past champion Novak Djokovic returns to the U.S. Open, and No. 2 seeds Roger Federer and Caroline Wozniacki are in action on a sweltering second day at Flushing Meadows.
The No. 6-seeded Djokovic faces Marton Ducsovics in his first match at the U.S. Open since losing to Stan Wawrinka in the 2016 final. The Serbian missed last year because of an elbow injury but is one of the favorites after winning Wimbledon in July and beating Federer in the final at Cincinnati this month.
Djokovic could face a quarterfinal matchup with Federer, the five-time champion who meets Yoshihito Nishioka of Japan in a night match.
Wozniacki is already the highest-seeded woman remaining after top-ranked Simona Halep lost on Monday.
A heat advisory is in effect in New York through late Wednesday, with temperatures in the mid-90s and heat index values in excess of 100 degrees (38 Celsius).