The Houston Rockets will officially protest their loss to the San Antonio Spurs, according to Jonathan Feigen of the Houston Chronicle and Tim MacMahon of ESPN:

The controversy surrounding the loss stems from the officials not allowing a dunk by Rockets guard James Harden that appeared to go through the hoop.

According to Feigen, Houston is contesting that the officials' interpretation was a “misapplication of the rule,” while the Rockets also contend that the crew wrongly failed to allow head coach Mike D'Antoni to use a coaches' challenge:

The Rockets prepared to file a protest of Tuesday’s loss to the Spurs, a person with knowledge of the team’s plans said, with an argument that will cite the James Harden dunk that did not count as an example of a “misapplication of rules.”

It will also cite subsequent errors in officials’ failing to grant a coaches’ challenge, though the primary argument is with points not being awarded following a made basket.

The Rockets had hoped the NBA would act without a protest, but had determined they will take the next step in order to trigger a league action, according to the individual familiar with the process.

The officiating crew admitted after the game that the dunk should have counted. Instead, the Spurs clawed back from a 15-point deficit to tie the game and send it into overtime. San Antonio would go on to win in two overtimes.

No protest has been upheld since (conveniently) the Spurs won a case back in 1982, so this is relatively unprecedented territory for the NBA.