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You would've thought partying was an Olympic sport the way Michael Phelps, 27, took over Las Vegas over the holiday weekend.

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The most vivacious retiree in the world began his retirement bash by raging at Surrender Nightclub on September 1 and continued his celebration at Encore Beach Club the following day.

Watch the video to see the most decorated Olympian in history rev up the crowd alongside Afrojack and DJ David Guetta.