"He was relentless. The bell would ring, he would be on you. The bell would ring, he stopped. The bell would ring again, he'd be right back on you," said George Foreman about Rocky Marciano on ESPN ...

The only heavyweight champion to retire undefeated, Rocky Marciano had a perfect 49-0 record. The boxing legend did not train ...

1956 -- Rocky Marciano retires as the undefeated heavyweight boxing champion. He finishes with a 49-0 record, including six title defenses and 43 knockouts. 1968 -- Jimmy Ellis wins the world ...

Beneath the knockouts and relentless pressure was a deeply intelligent fighter whose footwork, head movement, and infighting tactics were decades ahead of their time. This is the full breakdown of how ...