STATE COLLEGE, Penn. - For the second straight muggy Saturday, Notre Dame's offense was sluggish.
And for the second straight week, its defense wilted in the heat in the fourth quarter.
The Irish were competitive early, but couldn't move the ball consistently and fell to 0-2 with a 31-10 road loss to No. 14 Penn State (2-0) Saturday.
"Obviously, on offense, we weren't doing enough to protect a defense that was, for three quarters, playing their butts off," Notre Dame coach Charlie Weis said.
The Irish mustered only 144 total yards - including zero net rushing yards - in the first start for freshman quarterback Jimmy Clausen. Clausen, who passed sophomore Demetrius Jones and junior Evan Sharpley on the depth chart, was sacked six times a week after the three quarterbacks took a combined nine sacks.
"We've been trying different things and trying different personnel groups, but the production just isn't there," Weis said. "Maybe we need to reduce what we do and try to find some things we can hang our hat on and do them."
Clausen completed 17-of-32 passes for 144 yards and an interception, with most of his attempts in the first half coming on short swing passes and screens.
"There were only a couple times the whole night that he wasn't looking in the right direction," Weis said. "... I'm not doing cartwheels, but I'm not displeased either."
Penn State, behind senior quarterback Anthony Morelli, had limited success on offense through 40 minutes but wore down the Irish defense late. The scene was reminiscent of a week ago, when Georgia Tech exploited an overworked Irish defense in the second half en route to a 33-3 win.
Morelli finished the game 12-of-22 for 131 yards with a touchdown and a costly interception on the Nittany Lions' opening drive.
Irish sophomore cornerback Darrin Walls intercepted a deep pass by Morelli and ran it back 73 yards to score the first Irish touchdown of the season - and give Notre Dame its first lead of the year.
Nittany Lion running back Austin Scott fumbled at his own 46 on Penn State's next possession, but a false start penalty and a sack left Notre Dame with no points from the drive.
It was a missed opportunity the Irish would regret.
Penn State wide receiver Derrick Williams returned a punt 78 yards for a touchdown to tie the score with less than a minute remaining in the first quarter. Williams broke attempted tackles by Irish defensive backs Terrail Lambert and David Bruton, juked his way out of trouble and zig-zagged downfield for the score.
"The other guys on the touchdown return did a great job," Williams said. "I had the easy part of just running. ... I just tried to make something happen."
Seven minutes later, Morelli found wide receiver Jordan Norwood for a 10-yard touchdown score to put the Nittany Lions ahead 14-7. Norwood caught the ball at the 5 and dove into the end zone, giving Penn State a lead it would not relinquish.
The Lions fumbled in their own territory late in the half, but again the Irish couldn't take advantage. Still, Weis said, Notre Dame was happy to go into intermission just one score down.
"After last week's performance, we wanted to make sure we went into the half with a chance to win the game," he said.
Penn State cornerback A.J. Wallace returned the second-half kickoff 68 yards, sending the home crowd into a frenzy, but the Irish defense stiffed. Scott was stuffed on third-and-one at the Notre Dame 18, and the Lions had to settle for a field goal by Kevin Kelly.
Notre Dame would get back within a touchdown - thanks to its own special teams. Tom Zbikowski returned a punt 47 yards down to the Penn State 7, but Notre Dame couldn't punch it in after two Clausen passes fell incomplete. Freshman Brandon Walker split the uprights to make the score 17-10.
Penn State answered right back, starting with the game's first big offensive play - a 51 yard pass from Morelli to wide receiver Chris Bell that pushed the ball down to the Irish 8.
Scott scored two plays after an Ambrose Wooden pass interference penalty on third down gave the Nittany Lions a new set of downs on the Irish 2.
After yet another three-and-out by Notre Dame, Penn State broke the game wide open with a 10-play, 62-yard drive on all rushes, capped by a five-yard touchdown run by Scott.
"If you don't start getting first downs and keeping your defense off the field, once you get to the fourth quarter, you start to wear down a little bit," Weis said.
Penn State finished the game with 295 yards of total offense, including 164 on the ground. Scott led the rushing attack with 28 carries for 116 yards and two touchdowns.
Down 31-10 late in the game, the Irish offense switched to the no-huddle and looked briefly sharp, going 65 yards in nine plays, including a 35-yard pass from Clausen to sophomore Robby Parris.
But Parris and freshman Duval Kamara dropped passes in the end zone, and Parris' drop resulted in an interception on fourth down. Even though the Irish didn't score, Weis said, the drive was important for Clausen's confidence.
"If you think about the grand scheme of things, you want the kid to leave with a decent taste in his mouth," he said. "At least he could leave the field at the end of game with those last couple drives, even though they didn't end up with points, feeling that he was doing better."
Notre Dame earned nine first downs and was 2-for-16 converting third downs Saturday. It opened the game with an 11-play, 48-yard drive, but sophomore Nate Whitaker missed a 50-yard field goal.
