BEIJING  The Michael Phelps gold medal count commenced early Sunday morning here with the 400-meter individual medley final, and his pursuit of a record eight golds began with a victory and a world record.

At 10:03 a.m., Phelps and his competitors dived into the pool at the Water Cube, and 4 minutes and 3.84 seconds later it was over. The morning after Phelps set an Olympic record in this event with a heat time of 4:07.82, a record that he said surprised even himself, he started his own countdown.

Image Michael Phelps with his gold medal after breaking the world record in the 400-meter individual medley. Credit... Doug Mills/The New York Times

One gold down, seven more to go, for an unprecedented total of eight. At 23, Phelps has been a household name in his sport for years, breaking through on the Olympic stage four years ago in Athens. He arrived in Beijing with a shot at breaking Mark Spitz’s record of seven gold medals in one Games.