Phelps says farewell in Rio

Michael Phelps is back for a sequel to his Olympic farewell.

This time, he insists, it really is goodbye.

After retiring and then un-retiring, Phelps will be in Rio as the first US male swimmer to compete in five Olympics. He is already the most decorated athlete in the history of the games, with 18 golds and 22 medals overall, and at age 31 remains the biggest star in a sport that will also feature teen sensation Katie Ledecky and an increasingly diverse pool of potential champions from around the world.