UCLA quarterback Nico Iamaleava is out for Saturday's matchup against Wisconsin, according to Wednesday's Big Ten injury report.
Iamaleava was forced from last week's win at Oregon because of a knee injury, and coach Bob Chesney said Monday that the Bruins had "serious concern" about it.
Iamaleava was injured in the second quarter of the 17-15 win and did not return in the second half. Backup Ty Dieffenbach came on to help orchestrate the victory for the Bruins, who improved to 5-0 and shot up to No. 12 in this week's Associated Press poll.
Iamaleava landed awkwardly on a scramble while being tackled and stayed down. After being tended to by athletic trainers, he was able to jog off the field.
As Iamaleava was tackled, the replay on the TV broadcast showed Oregon defensive lineman Bear Alexander twisting Iamaleava's helmet while the quarterback was going down. Once Iamaleava was down, Alexander appeared to punch him and strike his helmet. No penalty was called.
After Iamaleava jogged off, Dieffenbach threw an incompletion. Iamaleava was then able to return. But on the ensuing play he threw an interception, his third turnover of the first half.
When the Bruins emerged for the second half, Dieffenbach, a senior from Cal Poly who had not played all season, took over. Dieffenbach completed 3 of 6 passes for 43 yards and a touchdown.
Chesney on Monday called the Bruins' quarterback situation "decently fluid" between Dieffenbach and sophomore Madden Iamaleava ahead of Saturday's game. Madden Iamaleava, the younger brother of Nico, has appeared in three career games.
Nico Iamaleava, who has started every game since arriving at UCLA from Tennessee in spring 2025, has thrown for 982 yards and four touchdowns this season.
ESPN's Paolo Uggetti contributed to this report.