5. Bernardo Mercado
We don't usually think of Colombians as heavyweights, but the South American nation produced a dangerous big fellow in Bernardo Mercado, who fought a number of contenders in the 1970s and '80s. The 6-foot-4 Mercado might be best remembered for stopping two-time world title challenger Earnie Shavers in the seventh round of a thrilling fight in New Jersey in March 1980. It was a back-from-the-brink victory. Mercado looked like a sure loser when he was dropped by a right hand in the third round, but he got a break when a tear was noticed in Shavers' right glove -- the start of the fourth round was delayed by two minutes while a new glove was fitted. Amazingly, Mercado dominated the remainder of the fight after his near escape. Mercado had another big win in 1979 when he knocked out future heavyweight champion Trevor Berbick in the first round in Halifax, Nova Scotia. The Jamaican Berbick was at the time a resident of the Canadian Maritime city, and undefeated, but Mercado knocked him flat on his back with a right hand that the referee, Herb MacMullen, called "the hardest thing I've seen thrown."