RIO DE JANEIRO — At the Olympic swimming pool, the world’s best swimmers are never more than a few strokes from the pool wall and always within reach of a buoyant lane marker. They are constantly watched by countless coaches and assistants.

Also watching? Lifeguards. The Olympic swimming pool has lifeguards, just in case someone like Michael Phelps, winner of 18 gold medals, needs to be rescued.

“I’m dreaming of that possibility,” Anderson Fertes, a 39-year-old health-club lifeguard from Rio, said with a smile before starting his pool deck shift at the Olympic Aquatics Stadium. “I think about that.”

The odds are small. “It’s a one-in-a-million type of event, but we’re prepared,” Fertes said.

The lifeguards at the Rio Games have perhaps the best view in the house, as they are among the few people permitted on the pool deck. But they might not feel particularly useful.