Andre Dirrell, fighting with a tattoo of his grandfather's face on his back, assured the United States of two boxing medals by narrowly beating Cuba's Yordani Despaigne Herrera to advance to the middleweight semifinals.
Dirrell bloodied the Cuban's face in the third round and held on for a 12-11 win.
"I knew I could outbox him," Dirrell said. "I was extra nervous because the Cubans are great boxers."
Dirrell came from behind in the third round with a flurry and then listened to his grandfather and other family members when they told him to get on his toes and stay away to keep the lead with 25 seconds left.
"We knew it was going to be a chess match," U.S. Coach Basheer Abdullah said. "He was very patient and he played the chess match and won it tonight."
Dirrell, whose grandfather began teaching him to box at age 10 and then refused to let him quit the sport two years later, advanced to a semifinal match tomorrow against Gennadiy Golovkin of Kazakhstan.
Dirrell's grandfather, Leon Lawson, was watching from the stands. The former bodyguard and sparring partner for Muhammad Ali turned 64 this week.
"I'm aiming to please my grandfather," Dirrell said. "Besides the money, the gold medal and everything, I want to make him happy. This is what he said was his birthday present."