(NBC News) -- Less than two years after getting out of the pool, the most decorated Olympian ever in any sport is getting back in.
Michael Phelps is coming out of retirement and will compete at the Mesa Grand Prix in Arizona later this week. Phelps is entered in three events in his first competition since the 2012 London Olympics. Thursday he will swim in the 100-meter freestyle and 100-meter butterfly heats, and he is also slated for the 50-meter freestyle on Friday.
"Being able to be back in the pool, to go back to North Baltimore to swim with the group we have now...it's incredible," said Phelps.
Phelps, with 22 medals in three Olympics, earned six medals at the London Olympics and then gave up competitive swimming.