Arguably the biggest fight in history is almost here. Floyd Mayweather and Conor McGregor will go face-to-face Saturday night at T-Mobile Arena in Las Vegas, possibly in front of the largest pay-per-view audience of all time.

Showtime PPV has the TV broadcast, and coverage of the event technically starts at 7 p.m. EDT. The first of the three undercard fights doesn’t begin until 9 p.m. EDT, which means the actual fight time for Mayweather vs. McGregor will probably be sometime between 11 p.m. EDT and midnight.

It’s impossible to predict exactly when the bell for Mayweather and McGregor will finally ring. When Mayweather and Pacquiao set a record with 4.6 million PPV buys on May 2, 2015, their bout began at 11:55 p.m. EDT. In Mayweather's last bout, which saw him defeat Andre Berto by unanimous decision 23 months ago, the bell for the first round rang at around 11:30 p.m. EDT.

Both fighters made the 154-pound weight limit without a problem Friday night. Mayweather, who’s never weighed more than 151 pounds for a fight, came in at 149.5 pounds. There had been rumors that McGregor was having trouble cutting weight, but he tipped the scales at 153 pounds.

“I’m a professional,” McGregor told Showtime’s Jim Gray. “I made weight. Look at me. I'm in peak physical condition. I'm ready. I will be a lot bigger than him [on fight night].”

Conor McGregor Floyd Mayweather
Conor McGregor and Floyd Mayweather, pictured during their official weigh-in at T-Mobile Arena on Aug. 25, 2017 in Las Vegas, will start their super-fight late Saturday night. Getty Images

McGregor was primarily a featherweight in the UFC up until he won the 145-pound belt from Jose Aldo in late 2015. He jumped up two weight classes for his first two fights in 2016, weighing in at 168 pounds when he battled Nate Diaz at UFC 196 and UFC 202. In November, he won the UFC lightweight title from Eddie Alvarez, and it’s expected that he’ll defend that belt at 155 pounds if and when he returns to MMA.

The UFC lightweight champion is the naturally bigger fighter, standing one inch taller with a two-inch reach advantage. Giving up a little bit of size has never hurt Mayweather before, who enters the fight with a perfect 49-0 record.

Mayweather has been favored ever since betting odds were created for the fight, and a large portion of the boxing world isn’t giving McGregor much of a chance to pull off the upset. Mayweather has won his last seven fights by decision, though Saturday might represent his best chance in a long time to end the bout quickly.

Most of McGregor’s fights don’t last very long. He won his last fight via second-round TKO, and only his fights with Diaz have gone beyond the third round. UFC rounds are five minutes long, while Saturday’s rounds will be three minutes each.

No matter when the fight starts or how long it lasts, both athletes have a chance to earn more money than they’ve ever made for a night’s work. That will certainly be the case for McGregor, who’s been guaranteed a payday of $30 million. Mayweather will get a check of a $100 million.

The PPV sales will allow the fighters to make much more, and expectations are that the bout will generate somewhere between four million and five million buys.