Nick Marshall threw two touchdown passes, Auburn forced three turnovers and the fifth-ranked Tigers held on to beat mistake-prone No. 20 Kansas State 20-14 on Thursday night.Marshall finished with 231 yards passing for the Tigers (3-0), who were forced to the air by a Wildcats defense that was bent on stopping the run. The nation’s sixth-ranked rushing attack had only 130 yards on the ground, 200 less than its season average.Not that it mattered the way Kansas State (2-1) squandered its chances.Jake Waters threw for 245 yards, but he also tossed two interceptions — one in the Auburn end zone.