NEW YORK (CNNMoney) -- The chance of winning $1 billion in the NCAA brackets was always the ultimate long-shot - 9.2 quintillion to one by some estimates.
But the chance dropped to zero after the very first game Thursday for an estimated 84% of the fans who entered brackets in the billion dollar challenge..
That's when the University of Dayton upset cross-state rival Ohio State 60-59 in the first game of the tournament. Celebration for Dayton fans and students. The end of the dream for Ohio State -- and most of those thinking they actually had a chance at $1 billion.
The perfect bracket challenge was sponsored by Quicken Loans and Yahoo Sports, and backed by an insurance policy by Warren Buffett's Berkshire Hathaway. Neither Quicken Loans nor Yahoo are disclosing how many entries they have, although they're promising an update about how things stand after the first round.
The odds of anyone picking a perfect bracket are subject to debate. The 9.2 quintillion estimate assumes each team has a 50% chance of winning every game, which past practice suggest is not the case. Others have put the odds at 7.4 billion to 1, or 42 times worse than your chance of winning Powerball.
\"There is no perfect math...There are no true odds, no one really knows,\" Buffett told CNN in January when the challenge was announced.
One of the things that makes it so hard to pick a perfect brackets is that every year there are upsets like the Dayton-Ohio State game.
That wasn't the only upset Thursday. Yahoo's stats show 70% of fans picked Cincinnati to beat Harvard and 77% picked Oklahoma to beat North Dakota State. Those large majorities were disappointed in each case.
Taking the three big upsets together likely left only 1% of the entrants with perfect brackets -- assuming they didn't miss any of the other 13 games on Thursday. And Friday has 16 more chances for upsets.
It is likely that no one will make it out of the first round alive -- CBS Sports, which runs one of the bigger bracket challenges, reports that in the last two years the last perfect brackets were eliminated in the 22nd and 23rd games of the tournament. ESPN reports that of the roughly 30 million entrants it has had over the 13 years, no one has come close to a perfect bracket, and that only one person has had a perfect first round in the last seven years.
\"I don't want to say it's impossible, but it's basically impossible,\" said John Diver, director of product development for ESPN Fantasy
So Buffett probably didn't have to worry about paying $1 billion heading into the tournament. And he had even less worries after the first game. By sometime Friday night, he'll probably be able to put the money back in his pocket.