For nearly two decades ESPN Radio has filled four hours of its morning airwaves with the musings of Mike Greenberg and Mike Golic Jr. Collectively known as “Mike & Mike,” the show, which debuted in 2000, quickly became a fan favorite and has aired each morning on ESPN2 since 2006. But those days are about to end, according to Sports Illustrated , which reported on Thursday that Greenberg is poised to headline his own show on ESPN, without Golic by his side.