Whitney's goal with less than 3 minutes left in the second period gave Phoenix a 2-1 lead and Vernon Fiddler added an insurance goal early in the third for the Coyotes.
Martin Hanzal scored and Ilya Bryzgalov improved to 5-0-0 in his last five starts, stopping 29-of-31 shots to boost Phoenix past Anaheim and Dallas and into the top spot of the division with 69 points (30-19-9).
Marcus Johansson and Matt Bradley scored and Michal Neuvirth made 15 saves as the Capitals lost to Phoenix for a fifth straight time.
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