Senior Greg Minnich scored on an offensive putback with 10 seconds left to give Williamsport a 70-68 edge.
"I was just thinking I had to come up with a big play," said Minnich, who finished with a game-high 24 points. "I pretty much had it the whole way."
South turned the ball over on the ensuing possession, and Jeff Ryan sealed the game with a layup for a two-possession lead. The Rebels turned it over four times - a backcourt violation, an errant pass, a traveling violation and a Wildcats steal - in the final minute.
"We played good for three quarters, it was just a situation at the end of the game where we didn't stand up to the pressure," Naylor said. "Williamsport is just a tough team to have to open up with."
Both teams relied on defensive pressure and traps in an attempt to disrupt the opposing offense. As it turned out, South was a bit too aggressive and piled up 26 team fouls - two starters fouled out.
Of their 36 free-throw attempts, the Wildcats hit only 23 (63.9 percent), but they connected on 14 of 26 shots from the field in the second half (53.8 percent). Sean Dixon and Eric Wilfong each added 12 points for the Wildcats.
"We made a conscious effort in the second half to not settle for jump shots," Mowbray said. "When you start concentrating on getting the ball inside, you're going to get better looks and create opportunities to go to the line."
South (0-1) scored the first five points of the game and led for the entire first half. Williamsport (2-0) took its first lead at 37-36 when Dixon scored coming off a back screen with 5:40 left in the third quarter. The lead changed hands five times before the end of the period and South took a 52-48 lead into the fourth quarter.
The Rebels hit 6 of 7 shots to open the final period and led 63-54 with 4:13 remaining when forward Alvin Roberson fouled out of the game. Williamsport (2-0) rallied for a 12-2 run to take a 66-65 lead with two minutes left.
After the final South timeout, junior Shane Santell got control of a loose ball and drained a 12-foot jumper from the left wing while being fouled. He hit the foul shot to give the Rebels a 68-66 lead with 1:35 left.
Williamsport answered by easily breaking the Rebels' full-court press, and Colby McCauley found Minnich for an easy basket to knot the game at 68. Williamsport scored the last six points of the game.
"It's going to take us getting back into the gym and working on what to do in the last two minutes," Naylor said. "It comes down to clock management and knowing what to do with the ball."
Reserve Steve Burnett led the Rebels with 16 points, Roberson had 10 and Santell, Chris Jackson and Bryce Bryant each added nine.