NEW YORK (CBSNewYork/AP) — Andy Murray was only briefly troubled by Nick Kyrgios in the most-anticipated match of the U.S. 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.

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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.

Kyrgios has drawn a lot of unwanted attention lately, stemming from his trash-talking to Stan Wawrinka during a match in Montreal last month. Kyrgios was caught by courtside microphones making a comment about Wawrinka’s girlfriend, earning a fine from the ATP, which also put the 20-year-old Australian on six months’ probation. That warning applies only to ATP events, though; Grand Slam tournaments such as the U.S. Open are sanctioned by the International Tennis Federation.

Even for Kyrgios, this was unusual.

At changeovers while dropping the first two sets of his first-round U.S. Open match against Murray, Kyrgios _ a talented and attention-grabbing 20-year-old Australian _ leaned back in his chair and rested his head, looking as if he might be ready to take a nap.

He apparently never did fall asleep, though, because he kept playing, well enough to take the third set and force a fourth.

More players have stopped playing during matches because of injuries or illness during the first round of the U.S. 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 during matches Monday and Tuesday at Flushing Meadows _ with the first round still yet to be finished.

The previous mark for most retirements during any round at any major was nine at the 2011 U.S. Open.

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Among the 10 men and two women pulling out so far were five retirements Tuesday: Marcos Baghdatis, Ernests Gulbis, Thanasi Kokkinakis, Aleksandr Nedovyesov and Marina Erakovic.

Roger Federer gives credit where credit is due.

The 17-time major champion says several past opponents helped him become the player he is.

Federer mentioned Andre Agassi and Lleyton Hewitt as the first to force him to improve.

Those two “really made me feel like a bad baseliner to an extent, until I realized I had to move better and be more consistent, have variation in my game,” Federer said after his first-round victory at the U.S. Open on Tuesday.

Federer picked up pointers on serve-and-volley tactics from Pete Sampras and Tim Henman, for example.

And more recently, Rafael Nadal made Federer’s backhand better.

“Rafa challenged my backhand the most throughout my career,” he said. “I had to return differently every single time I played against him.”

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