When American television presenter Bill Boggs tried to compete with a swimmer in the pool, little did he know that he would be up against Olympic gold medallist Michael Phelps.

Boggs, 65, who used to swim competitively, was doing laps at the New York Athletic Club when he noticed someone swimming at a very fast pace.

“The guy next to me is like a shark ... he’s pushing off the wall swimming the length of the pool under water, while kicking on his back. ‘Hmm,’ I think, ‘this guy’s good’,” the New York Post quoted Boggs as saying.

“We hit the wall together at one point and I give it all I’ve got to stay with him, and after three strokes I look up and he’s already coming back,” he recalled.

The speed demon left the pool before Boggs finished, and when he got out, the attendant let him know who he was competing with.

“You were trying to race Michael Phelps,” the attendant told him.