Debutants South Sudan, led by NBA player Royal Ivey, were looking to inflict only the seventh defeat on Team USA at an Olympics and they came out strongly, capitalising on some early American mistakes to edge ahead in the first quarter.
But it did not last long as poor shooting and constant fouls saw the defending champions lead by 19 points at the break.
Stylish as ever and fully recovered from injury, three-times Olympian Kevin Durant showed all his ability on the free shots, netting eight out of nine to delight the thousands of fans.
The crowd were also thrilled to see the amazing dunks of Lebron James and Derrick White, who combined for 22 points.
Serbia made easy work of Puerto Rico in the earlier Group C match. In a one-sided affair, Filip Petrusev and Nikola Jokic were the dynamic duo who combined for 29 points.
In the second round of Group A in the women's basketball earlier on Wednesday, Spain survived a nail-biting finish against Puerto Rico to win 63-62 and Serbia downed China 81-59.
Spain and Serbia, who will meet in the final pool game on Saturday, both earned a place in the quarter-finals.
Megan Gustafson turned in another stellar performance with 18 points and 13 rebounds for Spain.
The Puerto Ricans, who overcame the Europeans in the third quarter, took an impressive 19-point lead, limiting the European side to five points.
But the pressure proved too much for them in the final quarter and Laura Gil sealed the victory for Spain on a free shot with one second left.
Serbia defeated China thanks to a brilliant combination of 12 points from Tina Krajisnik and 15 from Yvonne Anderson.
The strength of the Europeans was clear from the start as they opened up a six-point lead in the first quarter. China, however, rallied before the break and levelled at 22 all.
But the team, who had Chinese Basketball Association president and ex-NBA Houston Rockets player Yao Ming supporting on the bench, coul not withstand the Serbs' second-half surge.
China and Puerto Rico have one last hope of progressing when they meet on Saturday if they can pick up enough points to finish in the top two third-placed teams of the group stage.
