(left) American Pharoah goes over the track during morning training for the Kentucky Derby at Churchill Downs on April 29, 2015 in Louisville, Kentucky. (right) WBC/WBA welterweight champion Floyd Mayweather Jr. works out at the Mayweather Boxing Club on April 14, 2015 in Las Vegas, Nevada. Mayweather Jr. will face WBO welterweight champion Manny Pacquiao in a unification bout on May 2, 2015 in Las Vegas.
Rob Carr/Getty Images (left)—Alex Menendez/Getty Images (right)
(left) American Pharoah goes over the track during morning training for the Kentucky Derby at Churchill Downs on April 29, 2015 in Louisville, Kentucky. (right) WBC/WBA welterweight champion Floyd Mayweather Jr. works out at the Mayweather Boxing Club on April 14, 2015 in Las Vegas, Nevada. Mayweather Jr. will face WBO welterweight champion Manny Pacquiao in a unification bout on May 2, 2015 in Las Vegas.

Most of the year, people pay little or no attention to boxing and horse racing. But on Saturday these sports—once dominant forces in American culture—will be at the heart of what’s being pumped up as the year’s biggest sports day.

Some are calling Saturday, May 2, the Greatest Sports Day of 2015. Down the line it could very well come to be viewed among the biggest days ever in sports history. According to a new Nielsen study, more than half (52%) of adults in the U.S. will watch, listen, or attend at least one of Saturday’s sporting events. Here are a few other indications showing just how huge Saturday will be for the sports world.