Defense -- yes, defense -- powers Irish

SOUTH BEND, Ind. -- Purdue had just driven the length of the field before throwing an interception. One play later, Notre Dame's Armando Allen was tackled for a safety, giving the ball right back to the Boilermakers against a gassed Irish defense.

On the sideline, Brian Kelly told the defense that he was putting the game on its shoulders. Clearly, Kelly showed his inexperience in his first game at Notre Dame.

Didn't he know that the Irish haven't been able to stop anybody in a couple of years, and that defense is the team's weak link?

Purdue would score again to slice the lead to 20-12 with 11:55 left. From there on, though, the defense did something that hasn't been seen around here in a while: it closed out the game.

"It's a new year," nose tackle Ian Williams said. "It's 2010."

It does seem like science fiction to say that Notre Dame won its opener on defense. But Purdue scored only one touchdown, and on its final two possessions with the game on the line, managed a total of eight yards.

Some other things rarely spotted during the Charlie Weis era also occurred. Irish defenders made sure tackles. Cornerbacks competed for the ball and prevented the big pass play (the Boilermakers averaged just 7.1 yards per completion). The defense got sacks and turnovers. And it overcame adversity.

"We just went out there played our hearts out for four quarters," said cornerback Gary Gray, who had nine tackles. "We've improved a lot, in all facets."

Purdue coach Danny Hope noticed the difference. He said last year's Irish defense under Jon Tenuta blitzed nearly every play and left huge seams for big plays. On Saturday, Notre Dame mostly contained quarterback Robert Marve even when he rolled out of the pocket looking downfield.

The defense got pressure on Marve from the guys up front and registered four sacks, or 20 percent of last year's total. Gray and Darrin Walls, heavily maligned in 2009, each helped create a turnover; Walls grabbed a pick, while Gray batted a pass near the goal line twice that Williams scooped out of the air.

They locked down the Boilermakers despite an early injury to starting safety Jamoris Slaughter and cramps that kept key outside linebacker Darius Fleming on the sideline most of the day. Star middle linebacker Manti Te'o even uncharacteristically whiffed on several tackle attempts.

"That never happens," fellow linebacker Carlo Calabrese said. "But the safeties were right there when he missed."

Kelly made a point to mention how many people had called the defense "slow" this offseason. He told them to go out and play fast and aggressive.

Clearly, Kelly has a lot to learn still about Notre Dame. Or maybe this really is an improved defense.

"I think we made a statement today," Williams said.