Kevin Durant rattled in the game-winner with 1.5 seconds to play on Saturday as Oklahoma City downed reigning NBA champions Dallas 99-98 in their Western Conference playoff opener.
"Man, it looked bad when it left my hand," Durant said of the shot that bounced high off the rim before dropping through the net.
"I'd been struggling all night with my shot, missing open ones. But thank the Lord that one went in," he said.
With no timeouts left, the Mavericks were unable to get a shot off at the buzzer.
Dirk Nowitzki had put the Mavericks ahead 98-97 with two free throws with nine seconds remaining.
But on an inbounds play after an Oklahoma City timeout, Durant threw up a shot over two Dallas defenders to give the Thunder the narrow victory in a re-match of last season's Western Conference finals.
Durant, the NBA scoring champion, finished the game with 25 points on 10-of-27 shooting. Russell Westbrook led the Thunder with 28 points and Serge Ibaka added 22 points and had five blocks.
Nowitzki, Most Valuable Player of last season's NBA finals triumph over Miami, led the Mavericks with 25 points, 11 of them in the final five minutes.
Jason Terry added 20 points off the bench and Shawn Marion scored 17.
Durant's basket recalled the teams' regular-season meeting on December 29, when he drained a three-pointer at the buzzer for a 104-102 Thunder win.
The Mavericks, who ousted the Thunder in five games in the conference finals last season and went on to beat the Miami Heat in the NBA championship series, had led most of the game, but couldn't quite put it out of reach as the tight battle came down to the wire.
"A lot of things didn't go well for us early but our team stuck together," said Thunder coach Scott Brooks. "We got down seven with three minutes left and had to play near perfect and we did.
"On the last shot I liked the fact that he drove to the basket and then pulled up. Great players make tough shots."
Durant said he "didn't want to settle for a three".
"I got it closer and was able to shoot a shot. I got enough arc on it to go in."
A Nowitzki jump shot had given gave Dallas a 94-87 lead with 2:30 to play.
Durant made a brace of free throws and after Nowitzki missed a three-point attempt Ibaka completed a three-point play.
James Harden then stripped the ball from Nowitzki and handed off to Durant for a dunk that knotted the score at 94-94 with 1:27 remaining.
Two free throws by Ian Mahinmi put Dallas up 96-94, but Ibaka was fouled on a dunk and made the free throw to complete the three-point play to put Oklahoma City ahead again, 97-96.
The remaining three Western Conference series begin Sunday, with top-seeded San Antonio hosting Utah, the Los Angeles Lakers hosting Denver and the Memphis Grizzlies at home to the Los Angeles Clippers.