TAMPA — UCF's quest for a second consecutive undefeated season took a substantial hit Friday afternoon at Raymond James Stadium.Knights junior QB McKenzie Milton, a fringe Heisman candidate who has guided the No. 8 Knights to a 23-game win streak, was carted off the field with what appeared to be a serious right knee injury with 11:17 to play in the first half against USF.Initial social-media reports and still pictures indicated Milton had suffered a discloation.Milton remained on the ground near the Bulls sidelined after being tackled by Bulls CB Mazzi Wilkins following a 5-yard gain. Doctors treated him several minutes as players from both teams gathered around him.He pumped his right fist skyward after being carted off; his right leg appeared to be stabilized in a yellow air cast.Milton, the quarterback for 22 of its 23 consecutive wins, ranks second in the American Athletic Conference in total yardage (318.7 ypg). Regardless of today's outcome, the No. 8 Knights host Memphis — winner of four in a row — in next weekend's AAC title game.USF, meantime, found itself down a quarterback before kickoff. Junior Blake Barnett, is dealing with shoulder and ankle injuries, and didn't suit up.