The Dallas Mavericks are facing an NBA investigation after leaving out key players against the Chicago Bulls despite being in play-off contention.
Kyrie Irving was among those omitted, while Luka Doncic only played 12 minutes of Friday's 115-112 defeat.
The loss ended their play-off hopes but improved their chances of getting a top-10 pick in this summer's draft.
That led to accusations of 'tanking' - playing a weakened side in order to lose and improve their draft chances.
"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 on Saturday.
A lower finish in the overall standings gives the Mavericks a better chance of a top-10 pick in the draft, boosting their hopes of signing highly-rated French teenager Victor Wembanyama.
Dallas said Irving, Tim Hardaway Jr and Maxi Kleber were all nursing injuries while Josh Green and Christian Wood were being rested. All five players - plus Doncic - featured in Wednesday's win over the Sacramento Kings.
Coach Jason Kidd said before the game that the decision to rest players was made by owner Mark Cuban and general manager Nico Harrison.
Speaking after the game, Kidd said: "It's not so much waving the white flag. It's [that] decisions sometimes are hard in this business. We're trying to build a championship team. With this decision, this is maybe a step back. But hopefully it leads to going forward."
Meanwhile, Anthony Edwards top-scored with 33 points as the Minnesota Timberwolves secured at least a ninth-place finish in the Western Conference with a 151-131 win over the San Antonio Spurs on Saturday.
Utah Jazz are out of play-off contention but ended their home season with a 118-114 win over the Denver Nuggets, who have already clinched the number one play-off seed in the Western Conference.
Kawhi Leonard scored 27 points as the Los Angeles Clippers beat the Portland Trail Blazers 136-125 to move into fifth place in the Western Conference with the same record as reigning champions the Golden State Warriors.
Their fight to avoid the play-in for the seventh-10th-placed teams will come down to the final day of the regular season on Sunday, when every NBA team will be in action.
