Ninth-ranked John Isner, fatigued after a first-ever Grand Slam semi-final at Wimbledon and an Atlanta title run, lost to 152nd-ranked Noah Rubin on Thursday at the ATP and WTA Washington Open.
Rubin, a 22-year-old American who lost to Isner in the French Open's first round, beat the second seed 6-4, 7-6 (8/6) at the rain-hit US Open tuneup event.
US second seed Isner blamed his low-energy outing in part on his busy recent schedule and also on the showers that delayed his opener to Thursday after an opening bye.
"For me, this could very well be a good loss. I need a little rest," Isner said.
"There are some big tournaments coming up. I want to be full of energy for those. It's a blessing in disguise. That's the mentality I have to have."
"I've felt better but I've also won matches when I've been a little low on fuel."
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