JR Smith had already come up with one of the most boneheaded plays of the NBA season to cost his Cleveland Cavaliers in game 1 of the NBA Finals.

With scores tied at 107-apiece and just under five seconds on the clock, Smith grabbed a rebound as teammate George Hill missed a free throw.

But instead of putting up a quick shot, or waiting to be fouled, he sprinted towards the safety of the halfcourt — forcing overtime, where the defending champions Golden State ran roughshod over Smith and the Cavaliers to take game 1 124-114.

Smith was admonished by superstar teammate LeBron James, who scored 51 points and appeared to be told by Smith “I thought we were ahead”.

Cavaliers coach Tyronn Lue added weight to that theory post match when he confirmed Smith thought they held a slim lead.

But Smith, when cornered by journalists, changed his story.

“I was trying to get enough to bring it out to get a shot off,” Smith said.

“I knew we were tied, I thought we were going to call time-out. If I thought we were ahead, I’d have held onto the ball and let them foul me.”

Lue explained his star had simply made an error in game management and questioned whether he would’ve been able to close the game out had he been aware of the situation.

“He thought it was over. He thought we were up one,” Lue explained.

“Who knows if JR would have made the lay-up anyway.

“It was tough. He could have had a little floater. Somebody was there. You think about calling a time out and then LeBron was open for a second and it all happened so fast.”

James was frosty when discussing the play, but insisted he hadn’t spoken to Smith about it.

ESPN commentator Stephen A. Smith said it was “braindead and idiotic”.

“This is one of the most brain dead, idiotic things I have ever witnessed in the NBA,” Stephen A. Smith said.

“My lord, I cannot believe the mistake he made.”