At the end of day two, more players have stopped playing during matches because of injuries or illness during the first round of the US Open than in any round at any Grand Slam tournament in the professional era. With the temperature topping 90 degrees, a total of 12 men and women have retired - half of the top 10 seeds in the women's draw are already out.

With seventh-seed Ana Ivanovic, eighth-seed Karolina Pliskova and 10th-seed Carla Suarez Navarro all eliminated on Monday, a day after third-seeded Maria Sharapova withdrew because of a leg injury, sixth-seed Lucie Safarova crashed out. The French Open runner-up had a tough first-round matchup against 37th-ranked Lesia Tsurenko and lost 6-4, 6-1 in just 65 minutes.

Second-seed Simona Halep avoided an upset though, moving on in 47 minutes when Marina Erakovic retired in the second set. Halep was leading 6-2, 3-0. Petra Kvitova also advanced in the first round, needing about an hour for a 6-1, 6-1 victory over 126th-ranked Laura Siegemund, a qualifier from Germany. Victoria Azarenka's flashed her temper in a heated exchange with chair umpire Aurelie Tourte but that didn't stop her defeating Lucie Hradecka 6-1, 6-2. Caroline Wozniacki, last year's runner-up, also sprinted into the next round after she beat NCAA champion Jamie Loeb 6-2, 6-0 in just 67 minutes. Despite losing the first set Germany's Andrea Petkovic overcame Caroline Garcia 3-6, 6-4, 7-5.

Federer sharp, Murray through

In the men's draw, Andy Murray was only briefly troubled by Nick Kyrgios in the most-anticipated match of the US Open's first round. The third-seeded Murray, who won the title at Flushing Meadows in 2012, hit 18 aces and saved 11 of 14 break points en route to 7-5, 6-3, 4-6, 6-1 victory over Kyrgios on Tuesday night. Murray was mostly steady in the face of Kyrgios' various antics, which included appearing to take a nap during changeovers, smashing his racket and earning a warning from the chair umpire for cursing aloud.

Second-seed Roger Federer routed Leonardo Mayer of Argentina 6-1, 6-2, 6-2 in the first round. Federer saved the lone break point he faced and was done in a brisk 77 minutes. Federer arrived in New York after winning his 87th career title at Cincinnati, where he posted back-to-back victories against Andy Murray and Novak Djokovic.

Australian teen Thanasi Kokkinakis was in position to pull off an upset on his US Open debut, leading 12th-seeded Richard Gasquet two sets to one, when his legs started to cramp in the fourth. Barely able to move and serving underhand at times, the 19-year-old succumbed to Gasquet who clinched the fourth set and then won the first two games in the fifth before the 71st-ranked Australian had to retire, with just enough energy left to smash his racket.

Down two sets and a break, American Donald Young rallied to stun 11th-seeded Gilles Simon 2-6, 4-6, 6-4, 6-4, 6-4 in 3 hours, 34 minutes with a packed Court 17 urging him on. Fellow countryman John Isner got off to an impressive start beating Malek Jaziri of Tunisia 6-2, 6-3, 6-4. Germany's Dustin Brown threw a two-set lead against Dutchman Robin Haase to lose 4-6 4-6 6-3 7-5 6-4 on Tuesday.

jh/ (AP)