Through its first 10 games this season, all wins, Mount Pleasant had turned the ball over a total of seven times.
But Friday night in a WPIAL Class AA quarterfinal matchup against Beaver, the Vikings turned it over five times and suffered their first loss.
No. 12 Beaver (8-3) recovered four fumbles and picked off a pass in a 21-7 victory against No. 4 Mount Pleasant (10-1) at Plum.
"It was just one of those nights where the things didn't go our way," said Mount Pleasant coach Bo Ruffner. "When you turn the football over that much, you usually don't win football games."
The biggest turnover came early in the fourth quarter when Mount Pleasant was driving for a potential tying score.
The Vikings, down, 14-7, started the drive at their 5and drove 89 yards on nine consecutive runs. But, on the 10th play, Ryan Ballew had the ball knocked out of his hands by Beaver's Jordan Yates, who also recovered the fumble.
Two plays later, the Bobcats broke the Vikings' back when quarterback Alex Rowse found Dylan Goff streaking down the sideline for a 90-yard touchdown with 8:14 remaining.
"That's just been our makeup," said Beaver coach Jeff Beltz. "We had a matchup that we liked there and so we went to it."
It was the second time in the game Rowse and Goff hooked up for a long passing touchdown.
After Mount Pleasant took a 7-0 lead on a 2-yard touchdown run by Tyler Mellors in the second quarter Beaver faced a second-and-25 from its 26 on its next possession. But Rowse found Goff for 16 yards to make it a manageable third down, then hit Goff on a 58-yard scoring pass to tie the score, 7-7.
Rowse threw his second touchdown pass, a 10-yarder to Darius Wise, with just 41 seconds left in the first half to give the Bobcats a 14-7 lead.
"Alex just stays and plays within the system," said Beltz. "He's a great kid and an awesome leader. He just wants to win and that rubs off on the rest of the team."
Rowse finished with 13 completions in 21 passing attempts for 220 yards. He threw three touchdown passes, giving him a WPIAL-best 40 this season, and had one pass intercepted. Goff had five catches for 182 yards.
Mount Pleasant still had time to rally after Rowse's final touchdown pass. The Vikings drove inside the Bobcats 20 with more than six minutes left. But Ethan Charlesworth lost Mount Pleasant's third fumble inside Beaver's red zone to end the threat.
Mount Pleasant also fumbled on its final possession, as Mellors turned it over for the second time, to seal the Beaver win. Mellors finished with 148 yards on 29 carries, but the Vikings were held 121 yards below their season average of 408 total yards per game.
"Today, our defense played much better than the offense," said Rowse. "The defense gave us so many opportunities that we probably should have scored a lot more than what we did."
But Beaver scored enough to advance to the WPIAL semifinals for the first time since 2003. They will meet top-seeded Aliquippa on Friday.