Mitchell had heard negative things all week leading up to Friday's matchup against River Ridge.
"They said we can't handle them," first-year coach Brian Wachtel told his team after a 31-13 win.
Junior tailback Ricky Trinidad started strong, running back the opening kickoff 94 yards for a touchdown.
The Knights did not seem rattled, marching down the field for a score on a 55-yard touchdown run by sophomore tailback David Daubert.
Trinidad scored in the second quarter on an 85-yard run out of the Wildcat formation. Then Mitchell backup quarterback Anthony Moore hooked up with senior halfback Brandon Mundy on a 10-yard touchdown to put the Mustangs up 21-6.
But the Knights responded, taking advantage of a Mitchell fumble. Kenny Toce, who finished 6-of-12 for 54 yards passing and added 31 yards on the ground, led a scoring drive, capped by Trevor Hooker's 15-yard run. The Knights had a solid night on the ground with two backs getting 85 yards each - Daubert and Stavros Arianas.
Mitchell was held to a 27-yard field goal by Codi Folsom on the next possession. River Ridge had an opportunity to shrink the gap when it attempted a fourth-down conversion but Toce's pass was tipped out of the end zone.
Trinidad made the Knights pay as he took a sweep 74 yards to the end zone. He finished the game with 11 rushes for 225 yards.
"I'm just happy to get Coach the win," Trinidad said. "We worked so hard this summer."