Busting most of the nation's NCAA tournament brackets took all of one game.
When 11th-seed Dayton beat sixth-seed Ohio State on Thursday with a basket in the final seconds, the upset upended the elusive hope millions had to complete a perfect bracket.
Of the 11.01 million brackets submitted in ESPN's contest, 80.3% picked Ohio State to beat Dayton. The number of entries, incidentally, zoomed up from last year's 8.15 million.
The numbers weren't any better in Yahoo's Tourney Pick'em, where 83.7% of entries went with Ohio State.
The chances of picking a perfect bracket weren't good to begin with. There are 9,223,372,036,854,775,808 possible combinations. That's 9.2 quintillion. Taking into account basic knowledge about the tournament -- like No. 16 seeds not beating top seeds -- one DePaul mathematics professor estimated the odds at a more reasonable one in 128 billion.
The tournament, though, isn't forgiving.
Harvard's upset of Cincinnati later Thursday left 5.7% of ESPN's brackets perfect.
And the games are just getting started.