The bout followed another significant defeat for the highly rated Cubans when the United States featherweight Floyd Mayweather beat Lorenzo Aragon. Mayweather's 12-11 victory made him the first American to beat a Cuban boxer in the Olympics since 1976 when Leon Spinks, who went on to become the world heavyweight champion, beat Sixto Soria in the 1976 light-heavyweight final. The United States boycotted the 1980 Moscow Olympics and Cuba boycotted the following two Games.
The two defeats left the Cubans with seven semi-finalists who are guaranteed medals and the US team with six.
The Tongan, a relatively inexperienced fighter with 23 bouts to his name and whose last fight before the Olympics was in March, had been given no chance against the best super-heavyweight in the world's best amateur boxing team.
"When you're Cuban and you come to the Olympics, you're ready for King Kong," he joked later. Wolfgram staggered the Cuban in the first round, inflicting a standing count with 1min 47sec to go. A second followed with 15 seconds remaining in the first round as the Tongan felled the Cuban with a left.
Belfast's Damaen Kelly could not produce another big finish and missed a flyweight medal. Kelly lost 13-6 to the world No 1, Bulat Dzumadilov, in the quarter-finals.