Stephanie Lawrence had picked off 10 rebounds to lead North Carolina, but she was struggling offensively, having missed all three of her shots.
Only five seconds remained in overtime at Chapel Hill, N.C., Sunday, and the Tar Heels were behind by two points when she launched No. 4.
It was good from three-point range, giving North Carolina a 74-73 victory over Alabama in the second round of the NCAA women's Mideast Regional. The Tar Heels (23-6) advanced to the semifinals, where they will face Tennessee in Iowa City, Iowa.
Lawrence never hesitated.
"It was just instinct, habit, going through the motion," she said. "I didn't really even think about it. I just shot it. I knew it was going in."
Yolanda Watkins' three-point play with 29.2 seconds to play had given Alabama (22-9) a 73-71 edge. North Carolina worked 10 seconds off the clock before taking a timeout.
Tonya Sampson, who led North Carolina with 30 points, drove the ball up the right sideline, stepped inside the three-point arc and fired an 18-footer that glanced off the rim. In the scuffle for the rebound, Alabama's Sharrona Alexander threw the ball inbounds. Lawrence gathered it at the left sideline, turned and shot the winning basket over Watkins.
Watkins led Alabama with 29 points and 12 rebounds. She scored her team's last 12 points.
Alabama Coach Rick Moody said the winning shot was the worst possible scenario for his team.
"It was very, very difficult to go in there and look at your team and try to explain it to them," Moody said. "I know their gut hurts just as bad as mine right now. We won't forget this feeling.
"Next year, hopefully, we'll be playing at home ourselves and maybe that hole will grow bigger when we throw that desperation shot up there at the end."
In another Mideast game, at Auburn, the third-seeded Tigers (25-3) used used a second-half surge, sparked by Lauretta Freeman, to beat Louisville, 66-61. Auburn will play No. 2 Iowa in Iowa City on Thursday.
At Charlottesville, Virginia (25-5) got 24 points from Dena Evans and opened with a 13-2 surge in a 69-55 victory over Florida (19-10). The Cavaliers advanced to a regional semifinal game against Georgetown on Thursday in Richmond. . . . Averrill Roberts scored 19 points, helping Ohio State (25-3) to a 91-60 victory over Rutgers at Columbus, Ohio. Ohio State moves on to Richmond, Va., on Thursday to play Western Kentucky.
In Nacogdoches, Tex., Deneen Parker scored 17 of her 32 points in the first 10 minutes, leading Stephen F. Austin (28-4) to an 89-78 victory over Clemson (19-11). Stephen F. Austin advanced to a region semifinal game against No. 1 Vanderbilt on Thursday, again in Nacogdoches.