With one UCLA quarterback already watching in street clothes from the sideline, his replacement went down just before halftime Saturday.

Ty Dieffenbach, who had filled in so capably for Nico Iamaleava over the last few games, got sandwiched between multiple Michigan State defenders and appeared to suffer a lower-body injury.

Dieffenbach walked gingerly off the field at the Rose Bowl before the Bruins punted the ball to the Spartans on the next play.

No. 9 UCLA held a 14-7 halftime lead, scoring 14 consecutive points after Michigan State had taken an early lead.

Dieffenbach had completed 10 of 19 passes for 83 yards while also running 4 times for 14 yards before he went down. He’s been filling in for Iamaleava since Iamaleava suffered a left knee injury just before halftime against Oregon earlier this month.

Iamaleava underwent season-ending surgery this week.

If Dieffenbach is unable to return, the Bruins would turn to Madden Iamaleava, the younger brother of Nico Iamaleava.