Michael Phelps doesn't even need to get his swimsuit on until 8.30 p.m. on Friday. By the time he races in Rio, it will be after 9 p.m. Other nights, it's been close to midnight. That's got to mess with the schedules of Olympians, many of whom usually practise early in the morning. So what gives?

While it is the International Olympic Committee that draws up the schedule, there is no bigger influence than NBC Sports. It has paid $7.75 billion US, in exchange for the American broadcast rights to every Games through 2032. That's more than every other broadcaster has paid the IOC combined. At that price, you get a lot of influence.

The United States is the largest television market in the world — and has a clear interest in seeing key sporting events broadcast when the most Americans can see them. The five key sports, those with typically the highest viewership, are mostly held to accommodate American prime time. Swimming, beach volleyball and track and field are latest, often not until 11 p.m. Rio time (10 p.m. on the U.S. East Coast). The two others, gymnastics and diving, happen slightly earlier.

And it's not just a question of the time of day. NBC has the power to affect which month the Olympics are held. For instance, when Beijing first bid for the 2008 Games, they'd planned a mid-September start. When NBC heard of the plan, they saw a challenge to seizing as many American eyeballs as possible.

August in Beijing luckier for network

"There's NFL coverage on Sundays and Mondays, and college football is now on four or five nights a week," the then-chairman of NBC Sports Dick Ebersol told the New York Times. "All of that goes away if you start in mid-August."

NBC explained that to the IOC and, lo and behold, when Beijing held the Games, they began on Aug. 8. Many assumed the mystical importance of the number eight in Chinese tradition was a factor — the Games started on 8/08/08.

"But that's not really why the Olympics started then," Ebersol said.

Competition from live streaming

In previous Olympics, NBC has used tape delay for a number of events — holding video from the American audience until a more advantageous time when more people are watching and thus more money can be extracted from advertisers. But the proliferation of live video streaming and social media makes tape delay much harder.

One solution: start the events later. The results happen at the peak viewership moment.

Of course, there are spectators watching in the arenas, and not just those watching screens a continent away. It makes for very late events in the Olympic Park. But Brazilians aren't complaining — and neither is their main television network, Globo.

Brazilian soap operas keep time slots

A quarter of the entire population watches the evening telenovelas — Brazilian soap operas — which broadcast at 6, 7 and 9 p.m.

The network almost never pre-empts them. Not for elections and rarely for anything else.

"They did this only to show the (Olympic) opening ceremony," Brazilian TV critic Mauricio Stycer told CBC. "It was huge. It was really exceptional. Globo is very afraid of not showing the most popular telenovela."

And it has not interrupted those programs for any sport. Events are happening, but Brazilians can't see them live — frankly, they prefer the telenovelas to the Olympics anyway. So the late start for key events, which benefits NBC, doesn't hurt the Brazilian audience.

Neither does it seem to hurt Michael Phelps, the winningest Olympian of all time. He can break records and win gold at any time apparently. But the swimmer's success is so tied to NBC's, the network asked for his blessing before suggesting the schedule shift. He agreed.

Phelps has talked in interviews about how he has been able to keep late nights for events and then get up early the next day.

But it'll be back to mornings for the next Olympics four years from now in 2020. They're in Tokyo, where prime events will need to happen between 7 and 9 a.m. local time, if they're going to hit prime time back in the U.S.