LeBron James walked out of his news conference after facing repeated questions about Cleveland Cavaliers team-mate JR Smith and his bizarre brain fade in the NBA Finals opener.

It was a night to forget for Smith, whose gaffe late on played a role in Cleveland's 124-114 overtime defeat to the Golden State Warriors in Thursday's game one.

The scores were tied 107-107 with 4.7 seconds remaining in the fourth quarter when George Hill missed his second free throw and Smith grabbed the offensive rebound before he ran the ball out past the three-point line in an apparent attempt to run out the clock.

James, who finished with 51 points, and his Cavs team-mates urged Smith to turn around and attack the basket, but it was too late as time expired.

Head coach Tyronn Lue said Smith thought the Cavs were ahead, while the veteran guard insisted he knew the scores were level in the Bay Area.

Facing the media after the Cavs were outscored 17-7 in OT, James told reporters: "We have to move on. This game is over and done with. We had our opportunities.

"I'll never give up on JR Smith. I don't give up on any of my players or team-mates. That doesn't even need to be said."

Pressed further by a reporter on Smith's gaffe, James replied: "What do you mean what's my version?"

Asked if Smith thought the game was tied or if the game was won, James said: "How do I know that?"

The reporter then asked if the pair discussed the incident and James responded: "No. I said no already.

Warriors Take Game 1 In Overtime

"I knew we were down one. George Hill went up and made the first free throw. We got the offensive rebound. I thought we were all aware of what was going on.

"I don't know what JR was thinking. I'm not sure what you're asking."

Questioned on Smith's state of mind, James shook his head and said, "I don't know his state of mind" before dropping the microphone and leaving.