Iowa State says right tackle Jacob Gannon has left the team just two days before it hosts No. 20 Kansas State.
Cyclones spokesman Mike Green tells The Associated Press on Thursday that Gannon quit for "personal reasons."
Gannon, a three-time academic All-Big 12 selection, started eight games last season and was in the lineup for last week's 34-14 season-opening loss to North Dakota State.
Highly-touted redshirt freshman Jake Campos is expected to start in place of Gannon.