All the Applemen (2-5) could only muster a wind-aided 49-yard field goal by Andy Shutts by halftime.
"It's been like that with us for two years now," Jefferson coach Jay Kirby said. "Tonight we overcame that."
It was mostly because of McDowell. He ran for 73 yards on Jefferson's opening drive of the second half, finishing the eight-play, 84-yard drive with a 16-yard run through two tackles into the end zone. It gave the Cougars a 13-3 lead.
"They just said at halftime to hold onto the ball," McDowell said. "After that, the holes just opened up and I took off."
After an interception on Musselman's next drive, McDowell scored again from 13 yards out, with plenty of help from, a great block by receiver Kyle Wilt for a 19-3 game.
The Applemen finally got a first down on their next drive, but Jefferson stumped them again and scored again on Bryan Hyre's 1-yard run. It was set up by a surprise pass play from Hyre to Wilt for 14 yards on third-and-5.
It capped Jefferson's first win over Musselman since 1994, and sent the Applemen to their first five-game losing streak since 1966.
"That's the best McDowell's run all year. That's the best they've passed all year. That's the best they've blocked all year. That's the best they've played defense all year," Price said. "Put that all together, you'll see a good football team and you'll get beat."
McDowell received birthday congratulations from everyone on his way to the locker room, and he got a little bit more from Kirby - a compliment.
"Damon took over and really stepped up in the second half and went after it," Kirby said. "I think this is the one where he's finally found his potential.
Jefferson 26, Musselman 9
J-Damon McDowell 93 kickoff return (Chris Puller kick)
M-Andy Shutts 49 FG
J-McDowell 16 run (pass failed)
J-McDowell 13 run (run failed)
J-Bryan Hyre 1 run (Puller kick)
M-Ryan Horn 5 run (kick failed)
Records: Musselman 2-5, Jefferson 2-5.