Down one with 14 seconds left in regulation, freshman Taliah Cashwell buried a 3-pointer from the corner with no hesitation off a designed in-bounds play. The shot gave SC a 53-51 advantage.
Nitro's Savannah Shamblin sank two free throws, however, as she wisely drew a foul on the ensuing Wildcats possession. The made shots essentially forced overtime as neither team attempted a shot in the final 6 seconds.
During overtime, the Black Eagles struck first and maintained a two-point lead until Shamblin nailed a pull-up jumper with 38 seconds to tie the contest once again.
Villanueva's plays in the final 12 seconds at the line and then with a steal sealed the win for SC.
For Nitro, Shamblin paced the Wildcats with 19 points as the team's go-to scorer. Shamblin fought through SC's defensive pressure throughout the night to leave her mark.
When Shamblin couldn't do it herself, her teammates came through, as Nitro Coach Will Samuels said he instructed Shamblin to let others carry the load.
"I said they're going to come out and they're going to double team you, they're going to triple team you at times,'" he said. "'You got to trust us. These girls here, they're out here playing hard. They can do it. They're confident. Give them the ball, let them make the play,' and she did a great job of buying into that and really kept us in the game the fourth quarter."
Meanwhile, Cashwell carried the Black Eagles with a game-high 22 points off the bench.
South Charleston returns to action to play at Jefferson 2:30 p.m. Saturday, while Nitro next plays at Ripley 7:30 p.m. Tuesday.