According to media sources, Phelps will start his Olympic program with 400IM. He will swim a heat on Saturday at 10 a.m. and the final later that night.

Speaking to media Phelps said, “Standing for four hours and marching into the stadium isn't believed to be a good training technique for the most rigorous swimming event of the Games.”

"That is one of the downfalls swimmers have of competing early in the Olympics, but I kind of like going first,” he added.

Sources added that several athletes don’t march in the Opening Ceremony for the same reason.

Archers and other athletes with early games tend to sit out.