Heat guard Mario Chalmers saved his best game of the season for the biggest stage.

Chalmers had 20 points Tuesday in the Heat’s 103-97 victory against the Oklahoma City Thunder.

The Heat’s streaky point guard was 8 of 14 from the field and 4 of 8 from three-point range. He also had three rebounds and two assists in 37 minutes. Chalmers was averaging 6.5 points and 24.8 minutes per game before his Christmas Day breakout.

“No one ever doubts Rio in big games,” Heat coach Erik Spoelstra said.

“You want him in your foxhole when the pressure is high.”

Chalmers had 12 points in the first quarter, matching his season high.

His five consecutive points in the fourth quarter gave the Heat an 86-77 lead.

“We’re clearly a better team when he is at his best,” Spoelstra said. “You have to have everyone as a live offensive threat. Everyone has to have balance.”

Free-throw gap

The Thunder leads the league in free throws made per game, but that doesn’t explain the discrepancy in attempts in the Heat’s victory.

The Thunder attempted 38 free throws while the Heat attempted 19.

“They’re relentless,” Spoelstra said, “absolutely relentless, and if you don’t have a mind-set of early urgency and if your mind isn’t ready and your feet aren’t ready and you’re out of position, then it’s an automatic foul.”

The Heat was 2 of 2 from the free-throw line at halftime but adjusted and finished the game 19 of 19 from the line.

Christmas gifts

The NBA presented each player who played on Christmas with Jawbone wireless speakers. LeBron James gave each of his teammates a pair of headphones (Beats By Dr. Dre). Spoelstra gave each of his players the book Clutch by Paul Sullivan.

As far as presents for players’ children, it’s good to have friends. James hooked Mike Miller up with LeBron Xs for his kids. Dwyane Wade gave his children LeBron Xs as well.

Then there was Heat reserve Terrel Harris, who asked Miller for his shoes before the game. Harris is an avid sports memorabilia collector, apparently.

Christmas shoes

The flashiest shoes in the building belonged to Wade. Like the sun, the shoes could only be glimpsed through the eye’s periphery for fear of going blind. But not in a bad way, of course.

Wade’s new shoe with Chinese company Li-Ning is called Way of Wade.

In the words of Wade, the color scheme for Christmas Day was “Grinch green on candy-apple red.” But candy-apple red didn’t really do the shoes justice — unless, of course, those apples were radioactive.

In a shameless plug for his new shoes, Wade changed his sneakers at halftime. He played the second half with shoes of white and red. Wade’s shoe change apparently had nothing to do with his cramping in the second half.