ANN ARBOR, Mich. -- Michigan defensive tackle Ondre Pipkins will miss the rest of the season after tearing an anterior cruciate ligament in one of his knees during Saturday's win over Minnesota.
The team announced the loss Monday. Pipkins, a sophomore, had appeared in all five games, totaling seven tackles.
The 18th-ranked Wolverines play at Penn State on Saturday.
Michigan is allowing opponents to convert 41 percent of their third-down plays, ranking them 78th among Bowl Subdivision teams.
In Michigan's 42-13 win against Minnesota last weekend, the Golden Gophers were 8 of 15 on third-down conversions and put together scoring drives of 16, 11 and nine plays that ate up more than 20 minutes of game time.
"Those are money downs to us," said sophomore linebacker James Ross III. "We have to get off the field and set up our offense to score points. That's on us and that's probably our main focus going into this game (at Penn State) in practice is making those third downs a big deal and getting off the field."
The troubles on third down haven't resulted in an overall defensive breakdown. The Wolverines (5-0, 1-0 Big Ten) are still the ninth-best defense in the nation against the run (90.4 yards allowed), 13th in total defense (305.0 yards) and 27th in scoring defense (19.4 points).
Its nine forced turnovers, including four interceptions by sophomore cornerback Blake Countess, have helped mitigate the 12 turnovers committed by Michigan's offense. Devin Gardner threw nine interceptions in Michigan's first four games and the turnover-free game against Minnesota was the Wolverines' first since Oct. 1, 2011.
"I think this defense is coming around. Is it exactly where we need it to be? No," coach Brady Hoke said. "I don't want to say they played with better urgency (against Minnesota), because they played pretty well most of the year, especially in the red zone. I just think they're a work in progress because of some of youth that's out there."
The inexperienced unit could get a boost from the return of one of its leaders against Penn State (3-2, 0-1). The teams, who will play annually as Big Ten East Division rivals beginning next season, haven't met since 2010, when Penn State won 41-31 in State College, Pa.
Though a little coy about the likelihood of Jake Ryan's return during a Monday press conference, Hoke said doctors have cleared the All-Big Ten linebacker, who has been sidelined since suffering a knee injury in March. Hoke said Ryan is "wanting to play," but that the coaching staff will evaluate him throughout the week to be sure "he can do the things he's capable of doing."
Ryan led the team in tackles (88), tackles for loss (16) and sacks (4.5) last season.
Penn State gained just 70 yards rushing on 38 carries during a 44-24 loss at Indiana last week, though freshman quarterback Christian Hackenberg threw for 340 yards on a school-record 55 pass attempts.