MIAMI — Kawhi Leonard had 20 points and 14 rebounds, and the San Antonio Spurs dominated the Miami Heat again in a 107-86 victory Thursday night to take a commanding 3-1 lead in the NBA finals.

Tony Parker added 19 points for the Spurs, who can win their fifth championship with a victory at home in Game 5 on Sunday.

LeBron James had 28 points and eight rebounds for the Heat, but Dwyane Wade was just 3 for 13 for 10 points as the Heat were routed at home for the second straight game.

The Heat would have to become the first team to overcome a 3-1 deficit in the NBA finals to win their third straight championship.

Trying to take a 3-1 lead back home, the Spurs shot 56 percent in the first half and led by as much as 22 points against the Heat, who looked powerless to slow San Antonio’s ball movement.

Not quite as sharp as when they shot a finals-record 75.8 percent in first half Tuesday night, the Spurs were still plenty good enough to open another huge lead before a Miami crowd that was booing the home team in the final minutes of the second quarter.

The Spurs knew their defense had to be better, realizing their once-in-a-lifetime, 19-for-21 start in Tuesday’s 111-92 rout covered the fact that they allowed Miami to make more than 50 percent in the game.

The defense was definitely improved in the first half, holding Miami to 12 of 34 (35 percent).

At the end of their fourth straight season that went the distance, the Heat looked as if they might be running out of gas.

The Spurs missed their first three shots after needing 22 attempts to miss three times Tuesday.

They quickly got on track from there, running off a 13-2 spurt to open a nine-point lead, and that was the margin when they went to the second ahead 26-17.