Michael Phelps is set to make a comeback to the pool in Arizona later this month.

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Greatest Olympian of all time set to come out of retirement

Phelps scheduled to appear at event in Arizona later this month

"Baltimore Bullet" re-entered U.S. drug testing program last year

CNN  — 

Michael Phelps, the most decorated Olympian of all time, is set to return to competitive swimming less than two years after announcing his retirement.

Phelps, who has won a record 22 Olympic medals, will return to the pool later this month at the Arena Grand Prix at Mesa, Arizona, according to USA Swimming.

The 28-year-old will join a field including fellow Olympic gold medalists, Ryan Lochte and Katie Ledecky at the event taking place at the Skyline Aquatic Center from April 24-26.

Phelps called time on his career after winning four golds and two silvers at the London Games in 2012, but fueled speculation that he was preparing to stage a comeback after re-entering U.S. drug testing program last year.

Swimming’s global governing body FINA requires athletes intending to return to competition following their retirement to be tested “at least nine months before he or she expects to return to competition.”

The three-time Olympian wouldn’t be drawn on the subject of a return to the pool when quizzed last November telling the Associated Press (AP) that “nothing is set in stone. If I decide to keep going and swim again, then I’ll compete.”

Phelps, a regular tweeter with nearly 1.5 million Twitter followers, has yet to break his silence on the subject of his expected return. His last tweet was on Sunday congratulating Bubba Watson on his “sick win” at the Masters.

Read More: Phelps’ fairway to retirement heaven?

Known as the “Baltimore Bullet,” Phelps was without peer in the pool winning 18 Olympic gold medals including a record haul of eight gold at the 2008 Games in Beijing – one more than compatriot Mark Spitz won at the Munich Olympics in 1972.

He collected a further 27 gold medals in World Championships and a total of 58 gold, 11 silver and three bronze in all during his career and still holds three individual world records in the 100m and 200m butterfly and 400m individual medley.

Phelps’ next chance to add to his medal tally will come in July 2015 at the World Championships in Kazan, Russia with the ultimate goal, perhaps, an appearance at a fourth successive Olympics at Rio in two years time.

Read more: Bubba Watson dons Green Jacket for second time