Iowa State coach Matt Campbell says running back David Montgomery is ''day-to-day'' after suffering an upper arm injury late in last weekend's loss at TCU. Campbell says an MRI and x-rays were negative and that Montgomery was working out with the team on Sunday with what he described as adeep bruise. Campbell says Montgomery's status for Saturday's game at Oklahoma State is probable, saying it may hinge on how much Montgomery can deal with the pain. Montgomery is Iowa State's leading rusher with 334 yards and three TDs on 82 carries. But the Cyclones have struggled to run the ball even with the talented Montgomery in the lineup, ranking 126th out of 130 teams with just 89.3 yards a game.