When Michael Phelps entered the pool for his final career Olympic swim, the Japanese 4x100 medley relay team held a slight lead. When the race ended, the U.S. led by nearly two seconds.

Undoubtedly much of that is due to Nathan Adrian's blistering anchor leg, but the truth remains that the U.S. were behind when Phelps started his butterfly portion, and ahead when he finished at 3:29.35, and that's your awesome Michael Phelps legacy (along with the 18 gold medals).

For a handy master schedule of every Olympic event, click here.