With nothing to play for, the Americans led their opponent by only four points early in the third quarter before turning the game into a rout over the final 15 minutes.
The US (5-0), seeded first in Group B, next plays on Monday against Angola, the No. 4 seed from Group A.
Goran Dragic of the Phoenix Suns scored 18 points, and Slovenia surged into the elimination stage of the world championship with a 65-60 victory over Iran on Thursday.
The Slovenians (4-1) won their last three games after losing to the United States to take the No. 2 seed from Group B. They will face Australia, the No. 3 seed from Group A, on Sunday.
Miha Zupan added 15 points for Slovenia, while Sani Becirovic and Bostjan Nachbar each scored 10.
Hamed Haddadi of the Memphis Grizzlies finished a strong tournament by scoring 15 points for Iran, the Asian champion that went 1-4 in its first appearance in the world championship. Arsalan Kazemi had 13 points and 14 rebounds.
The Americans misfired on nine of 10 3-point attempts in the first half and failed to show any sustained stretches of good offense, an occasional problem for the team during the group stage. The Americans have time to clean it up, with three days off before playing their first elimination game.
Kevin Durant and Russell Westbrook each scored 14 points for the US team and Stephen Curry had 13. Marouan Kechrid scored 15 points and Macram Ben Romdhane added 11 for Tunisia, which went 0-5 in its first appearance in the worlds.
US coach Mike Krzyzewski played his starters the entire first quarter, which ended with the Americans up 19-13. The reserves went the whole second, and though they pushed the lead into double digits, Tunisia was within two in the final minute before the Americans got the final two baskets for a 39-33 lead.
Clearly taking advantage of the Americans’ lack of interest, Tunisia hustled to keep possessions alive, even ripping a couple of balls out of US players’ hands. But those extra possessions usually ended in missed shots, as Tunisia hit 28 percent after entering the game at 36 percent for the tournament, second worst in the 24-team field.
The Americans finally broke it open midway through the third quarter. An 8-2 burst turned an eight-point lead into a 55-41 advantage. Gordon and Curry made consecutive 3-pointers in an 8-0 spurt that extended it to 63-44 in the final minute of the period.
Meantime, Lithuania defeated Lebanon 84-66 to end its group stage campaign with a perfect record of five wins out of five.
Lebanon (1-4) had already been eliminated, its fate in the six-team group sealed on Wednesday with a defeat by Spain.
In what amounted to essentially a bonus game having already sealed top spot in Group D, Lithuania’s reserves nearly got as much playing time as its starters.
The reserves outscored Lebanon’s bench 24-10 in the first half as Lithuania took a 39-32 lead.
Guard Renaldas Seibutis led Lithuania with 17 points, and Martynus Gecevicius added 16. Rony Fahed scored 19 points to lead Lebanon in the teams’ first meeting in a major international tournament.