If there was any expectation of invincibility for the Americans heading into the Tokyo Olympics, it’s already gone — after Nigeria’s D’Tigers roared to a shock 90-87 win early Sunday morning.

D’Tigers pulled off the international shocker with a roster primarily filled of little-known NBA players that found a way to beat a group of All-NBA, All-Star and max-contract performers.

The 22nd-ranked nation by FIBA beating the No. 1-ranked team and three-time reigning Olympic gold medalists.

“I thought that the Nigerian team played very physically, did a great job in that regard and knocked down a lot of 3s,” U.S. coach Gregg Popovich said. “Give them credit.”

Gabe Nnamdi of Miami Heat led Nigeria with 21 points. Caleb Agada scored 17 points, Ike Nwamu added 13 and Nigeria outscored the U.S. 60-30 from 3-point range.

Kevin Durant, who had never before played in a loss for USA Basketball in 39 senior international games, had 17 points. Jayson Tatum added 15, Damian Lillard had 14 and Nigeria-born Bam Adebayo 11.

“Just goes to show that we have to play better,” Tatum said.

The Americans had gone 39-0 in their last three Olympic seasons — including pre-Olympic exhibitions — on their way to gold medals and had been 54-2 in major exhibitions since NBA players began playing for USA Basketball in 1992. Plus, they’d beaten Nigeria by a combined 127 points in their last two meetings, one at the 2012 London Games, the other a warm-up for the 2016 Rio Games.

Nigeria lost to the U.S. at the 2012 Olympics by 83 points. Lost to the Americans again four years later in an exhibition, that time by 44 points.

Not this time.

“Nigeria’s come a long way with their basketball,” USA Basketball managing director Jerry Colangelo said.

Ike Iroegbu — a former Washington State player who spent some time in the G League — hit a 3-pointer with about 1:15 left to put Nigeria up 88-80. Durant scored the next seven points for the U.S; a 3-pointer, two free throws following a turnover, then two more from the line with 16.5 seconds remaining.

Nnamdi made two foul shots with 13.2 seconds left to restore Nigeria’s 3-point edge. The Americans ran 9.7 seconds off the clock on the ensuing possession without getting a shot off, and Zach LaVine missed a pair of free throws — the second intentionally — with 3.5 seconds left.

Precious Achiuwa got the rebound for Nigeria, and that was it. It’s only an exhibition — but the upset was still of the massive variety.

Popovich heard the final buzzer and shook hands with Nigeria coach Mike Brown, the Golden State assistant, as the Americans walked off stunned.

The bigger scare was the scoreboard. Nigeria trailed only 43-41 at the half, led for long stretches of the opening 20 minutes, and simply wasn’t going away.