Kevin Durant scored 17 of his game-high 36 points in the fourth quarter as host Oklahoma City struck first in the NBA Finals, winning 105-94 over Miami.
Playing for his first championship, Durant was virtually unstoppable in the final frame, using a dazzling variety of shots to lead Oklahoma City back from a 13-point deficit.
He finished 12 for 20 from the field while adding eight rebounds and four assists.Russell Westbrook provided sensational support for the three-time NBA scoring champion, narrowly missing a triple-double with 27 points, 11 helpers and eight boards.
LeBron James had 30 points and nine rebounds in defeat for the Heat, who scored just 40 second-half points in the opener of their second consecutive NBA finals appearance.
Game 2 goes Thursday night in Oklahoma City.
Trailing by seven at the half, the Thunder used stifling defense to force three quick Miami turnovers that allowed them to trim the deficit to one with 7:48 remaining in the third quarter.
The Thunder briefly drew even before James answered with back-to-back tough layups and Shane Battier buried a 3-pointer - his fourth of the night - to put the Heat back ahead by five.James followed with a ferocious dunk, but the Thunder kept pace and eventually surged ahead for the first time on a driving Westbrook layup as part of a three-point play with 16.4 seconds remaining.
Miami misfired on its final possession of the frame as the Thunder went into the fourth up 74-73.
A Thabo Sefolosha layup on a smooth Derek Fisher pass made it a five-point game, and Durant knocked down a 3-pointer and a driving layup to give the Thunder their largest lead of the night at 89-83.
Westbrook added a pull-up 17-footer with 3 1/2 minutes left to stretch the advantage to double digits, and the Heat didn't challenge the rest of the way.
Dwyane Wade scored 19 points while Battier added 17 for Miami.The Heat used hot shooting to take an early lead, riding five 3-pointers - including three by the light-scoring Battier - to a 29-23 advantage after 12 minutes.
Miami stretched the lead to 13 before the Thunder mounted a late charge, with a Westbrook layup trimming the deficit to seven.
James led with 14 first-half points and Battier added 13 as the Heat carried a 54-47 edge into the break.
GAME NOTEBOOK: The Thunder had only two turnovers in the second half. ... Westbrook came into the night shooting just 31.3 percent (25-for-80) in his last four meetings with the Heat. ... James had all four of his steals in the first half. ... Durant hit four of the Thunder's five 3-pointers on the night. ... Battier posted his highest-scoring effort since pouring in 18 points March 2 against the Utah Jazz.