San Antonio played a nearly perfect first quarter, leading 41-25. Leonard shot 5-for-5 from the floor in the opening period, including 3-for-3 on 3-pointers, and 3-for-3 on free throws.
The Spurs led 71-50 at halftime, becoming the first team since the 1987 Los Angeles Lakers to score at least 70 points in a half in a playoff game.
It was also the largest halftime lead by a road team in an NBA Finals game since 1996. The Spurs went 10:15 of clock time without missing a shot, bridging the first and second quarters.
Miami shot 55.6 percent for the first half but still trailed by 21 points.
The third quarter was a 25-15 win for the Heat, who dominated on defense. After playing the worst half in franchise history in terms of opponent's shooting percentage, Miami clamped down in the third quarter, holding San Antonio to 31.6 percent.
NOTES: San Antonio is just 4-5 on the road in this year's postseason. ... The Spurs own each of the last two playoff road wins by visiting teams in Miami. They also captured Game 1 of last year's NBA Finals. ... The Heat have won 13 consecutive games after a playoff loss, a streak that will be tested Thursday. ... Entering Tuesday, 6-foot-11 F Chris Bosh led the Heat with 29 3-pointers made in this year's playoffs. In the two games in San Antonio, he averaged 18.0 points on 59.1 percent shooting, including 4-for-6 on 3-pointers. .... In two games in San Antonio, the Heat were plus-11 with F LeBron James on the floor vs. the Spurs. In 26 minutes without James, the Heat were minus-24. However, James finished minus-21 on Tuesday.