Nelsonville-York missed opportunities to close out the game and win in regulation. Alexander took the openings and made them count.
Spartans center Jack Hart added another triple-double to his season total as he paced Alexander to a 63-56 victory.
"That was his seventh (triple-double) last night. He holds the school record," coach Blaine Gabriel said. Michael Chapman added 20 points and six assists.
Most of Hart's triple-doubles have come at the end of the season - something that Gabriel said is a result of Hart becoming more active.
Even though Hart and Chapman produced, the Spartans still found themselves down. Gabriel changed the defensive scheme and gave his team the opportunity to cut into the Buckeye lead.
"We took care of the ball and increased the defensive pressure," Gabriel said. "We got a slow start but closed well."
Nelsonville-York coach Jay Kline saw the game swing in the opponent's favor at the four-minute mark.
"(We had) turnovers and missed shots. They made four shots in four straight trips," Kline said.
Even though the Buckeye lead evaporated, they still had an opportunity to win the game in regulation.
"We had chances in regulation. We had the shot that we wanted with six seconds left; it missed off the rim, and we almost got the putback," he said.
Going into overtime, Kline said his team seemed to be down while Alexander's attitude was up, and it used that to its advantage.
"It was a good game. We would have liked to have won, but we saw a lot of positive things," Kline said.
Alexander will square off against Crooksville in its first playoff game, and if the team wins it will play Southeastern.
Nelsonville-York will play Federal Hocking in its first game.
"We are looking forward to the tournament," Kline said. "We feel like we are on the edge of doing good things. We have a positive outlook."