Los Angeles Lakers superstar LeBron James will stay "locked in" and "even keel" during the NBA Finals as he vowed to respond to a Game 3 setback.

Jimmy Butler was the star of the show as the Miami Heat beat the Lakers 115-104 to reduce the deficit to 2-1 in the seven-match series.

James accepted he did not do himself justice against his former team at Walt Disney World in Florida on Sunday.

The four-time NBA MVP is not dwelling on that performance ahead of Game 4 on Tuesday, when the Lakers get a chance to move a step closer to a first title for a decade.

James said: "Until the series is completed, I kind of stay on edge, stay locked in on the job at hand.

"Obviously, no one wants to ever lose. You hate that feeling, especially when you know you didn't play your best, and I definitely wasn't at my best [in Game 3] from an individual standpoint.

"So, I take that responsibility, and I take that with a lot of passion and understanding of how I can be much better in the following game.

"Throughout the postseason, I stay even keel.

"As I've grown in this game and I've grown over the years, I kind of stay even keel, understanding that there's always another opportunity to get better."