McNamara, a transfer from Michiga, left the field on a cart with his knee wrapped. He was injured while scrambling out of the end zone and falling awkwardly at the Iowa 2-yard line. McNamara appeared in street clothes on crutches along the Iowa sideline in the second half.
He completed 3-of-5 passes for 46 yards with no touchdowns or interceptions. Deacon Hill, a Wisconsin transfer, replaced McNamara and led Iowa to its first touchdown drive of the game, capped by a 3-yard pass to tight end Erick All.
McNamara started for Michigan in 2021 and helped the team to a Big Ten championship and its first-ever College Football Playoff appearance. He and J.J. McCarthy competed for the starting job entering the 2022 season, but McCarthy emerged as the top choice and McNamara missed most of the season with a knee injury. He transferred to Iowa in December.
The senior entered Saturday's game with 459 passing yards, four touchdowns and three interceptions, completing 50.6 percent of his pass attempts. He was limited in spring practice because of his knee injury and missed part of preseason camp with a quad injury, but returned for the season opener.