Inside Errol Spence's legendary sparring match with Floyd Mayweather that put 'The Truth' on path to greatness

The pair clashed a decade ago in Mayweather's gym where Spence had to earn the former P4P great's respect

If there's a story that best illustrates one of the most dominant characteristics of what makes unified welterweight champion Errol Spence Jr. so great -- his competitiveness -- look no further than a 10-year-old sparring session against Floyd Mayweather Jr. 

Boxing has long been protective about bringing to light what happens behind closed doors when top fighters, who might still be working their way into elite fighting shape during training camp, focus on specific skill building in sparring sessions not meant to produce a winner -- and certainly not meant for public consumption or gossip. 

This is one of the sport's most celebrated and unwritten rules.