Murray withdrew with a sore left hip from the year's final Grand Slam that starts tomorrow on the New York hardcourts, joining 2016 winner Stan Wawrinka, Novak Djokovic, 2014 runner-up Kei Nishikori and Canada's Milos Raonic among the injured.
"Don't forget we're not 21 anymore," said Nadal. Stan is 32. I am 31 and a half almost. Novak is 30. Andy is 30. We are not that young anymore, so it's normal that we had some things. That's coincidence that it happens at the same time."
"Don't forget that Sampras probably at my age was not playing tennis, Borg was not playing tennis. A lot of great players were not playing tennis at our age," Nadal said. "Is normal that we are still playing, we try our best, but it's normal that we have more troubles during this."
Asked if the schedule needed to be trimmed to ease the workload, 19-time Grand Slam champion Federer took that idea to extremes.
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"You can cut down the season by half and then if there is an injury we cut it down half again, and at the end we play two months of the year eventually and we'll still be injured because now we're not playing enough," Federer said.
"I don't think there needs to be that much addressing, because the players they have the option not to play as much."
Nadal cited different ball contracts for the US Open and its main tuneup events as a problem that could be resolved.
"That's very bad for the wrist, for the elbow, for the shoulder. That's bad," Nadal said. "There are contracts but there's some ways that you can fix it."
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Nadal supported an experimental change used in qualifying to allow coaching, but drew the line at a 25-second shot clock.
"Depends on what the fans want. If the fans want short points and players playing without thinking, only going for the shots, maybe is good," Nadal said.
"If you want to have matches like the three finals I played here with Novak, the kind of match the crowd is more involved because the points are so long, well, you cannot expect play 50 shots' rally and in 25 seconds be ready to play the next point.
Most assuredly, New York fans love nothing more than a show and Nadal can't wait to give them one when he opens play Tuesday.
"Excited to start the US Open," he said. "Doesn't matter if you're seeded one or 20, for me always is special to play here.