Nigeria defeated a roster stacked with All-N.B.A. players on Saturday, becoming the first African team to beat the U.S. men’s national team.The U.S. men’s basketball team was upset by Nigeria on Saturday evening in its first exhibition game ahead of the Tokyo Olympics, a stunning outcome even if the effects are more symbolic than likely to affect the United States’ eventual gold medal hopes.Nigeria defeated a Team U.S.A. roster stacked with All-N.B.A. players, 90-87, at Mandalay Bay Arena in Las Vegas. It was the first win by an African team over the U.S. men’s national team.The loss drops Team U.S.A.’s record to 54-3 in exhibition games held since 1992, when N.B.A. players were first allowed to play in the Olympics. The team had not lost an exhibition game since 2019, a 98-94 upset by Australia ahead of the FIBA World Cup.Only nine years ago, the United States beat Nigeria, 156-73, at the 2012 Olympics in London.In Saturday’s stunner, Kevin Durant scored a team-high 17 points for Team U.S.A. Jayson Tatum had 15 points, and Damian Lillard added 14.The trio was held to 9 of 30 shooting from the field, and their teammates looked out of sync after the recent end of the N.B.A. postseason and a short turnaround from the previous season. Players like LeBron James and Stephen Curry dropped out of consideration for the Olympics, but the roster is still stacked with players who are expected to win gold in Tokyo.Nigeria’s roster includes a handful of N.B.A. players, including Chimezie Metu of the Sacramento Kings, Josh Okogie of the Minnesota Timberwolves and Miye Oni of the Utah Jazz. The team is coached by Mike Brown, a Golden State Warriors assistant.Nigeria converted nearly half of its 40 3-point attempts against Team U.S.A.Ike Iroegbu, who played at Washington State, made a 3-pointer with just over a minute left and pushed Nigeria to an 88-80 lead. Durant responded with seven straight points. The Miami Heat’s Gabe Vincent, who scored a game-high 21 points, sank two free throws with 13.2 seconds left, helping cement the upset as Team U.S.A. failed to execute a play out of a timeout called in the game’s final seconds.“That loss means nothing if we don’t learn from it, but it can be the most important thing in this tournament for us to learn lessons from it,” the U.S. coach, Gregg Popovich, told reporters afterward.Milwaukee’s Jrue Holiday and Khris Middleton and Phoenix’s Devin Booker are set to join the roster for the three-time defending gold medal-winning Team U.S.A. at the conclusion of the N.B.A. finals. More