His times in the 100m and 200m butterfly are the fastest times in the world since 2009 .
At the U.S. Summer Nationals , Michael Phelps proved why he 's the greatest swimmer of all time .
Michael Phelps ' times in the 100m and 200m butterfly are the fastest times in the world since 2009 .
At the U.S. Summer Nationals , Michael Phelps proved why he 's the greatest swimmer of all time .