At the 100 - meter mark , Phelps was once again just 0.19 seconds ahead of his world record pace .
At the first 50 , Phelps was just 0.19 seconds ahead of world record pace .
At the 100 - meter mark , Phelps was once again just 0.19 seconds ahead of Phelps ' world record pace .
At the first 50 , Phelps was just 0.19 seconds ahead of world record pace .