"The NBA commenced an investigation today into the facts and circumstances surrounding the Dallas Mavericks' roster decisions and game conduct with respect to last night's Chicago Bulls-Mavericks game, including the motivation behind those actions," NBA spokesperson Mike Bass said in a statement.
League rules include measures against "tanking" which stipulate an owner may not "attempt to lose or control the score of any game."
Although Dallas' chances of making the play-in had dwindled dramatically in recent days, they still had a shot at the Western Conference 10th seed - the final berth in the four-team play-in for the last two play-off berths.
So it raised eyebrows around the league when the Mavs, who had listed no players as questionable or doubtful on early injury reports for the game, declared late Friday morning that five players would sit out.
That included regular starters Kyrie Irving - who has been playing through foot pain - and Tim Hardaway Jr. as well as key reserves Josh Green, Maxi Kleber and Christian Wood.
Shortly before the game, head coach Jason Kidd said that star Luka Doncic would only play the first quarter, an apparent nod to the fact that the team was celebrating his Slovenian heritage on Friday night.
Kidd told reporters before the game that the decision had come from Cuban and the Mavs' front office, while players and coaches had "all said that we want to have the opportunity to find a way to get in (to the post-season).
"We were going to play until told otherwise," Kidd said. "And today is the day that we've been told that we're going to do something different."
Kidd said the Mavs players who were on the floor wouldn't "cheat the game" and indeed Dallas started off hot and led 67-54 at halftime.
But rookie Jaden Hardy, who scored nine points in the first half and drained a long-three-pointer at the half-time buzzer, didn't play in the second half - apparently another fact that got the attention of the league.
The Mavericks certainly weren't the only team holding out top players on Friday as multiple play-off-bound clubs sat down their stars as they began to focus on the post-season.
'Players don't do that'
But NBA watchers immediately speculated that Dallas' move was a purposeful attempt to protect their first-round selection in this year's NBA draft in May.
They still owe a first-round pick to the New York Knicks as part of the trade for Kristaps Porzingis in 2019. But if the draft lottery determines they will have a top-10 selection, they don't have to give it up.
A lower finish in the overall standings would give them better odds of drawing a top-10 pick in the lottery.
Cuban, who was fined $600,000 (£483,000) in 2018 for admitting the Mavericks were tanking, said Wednesday his players wouldn't stand for the strategy.
"The guys don't want to do that," Cuban said. "Players aren't going to do that. Players don't do that."
Cuban, whose Mavs reached the Western Conference finals last season and were fifth in the West in February when Irving arrived in a trade from Brooklyn, did not immediately comment publicly on Friday's game.
