SOUTH BEND | Jimmy Clausen threw the ball 51 times Saturday, setting various personal and program records by game's end. But it was from the ground that he witnessed his team's final demise.

Down a touchdown and backed deep into their territory, the Irish steadied themselves for their next fourth-quarter miracle. But Navy's only two sacks of game came back-to-back and drove Clausen into his own end zone, registering a safety that would be the difference in a stunning 23-21 upset Midshipmen victory at Notre Dame Stadium.

No. 19 Notre Dame (6-3) fell behind early thanks to a pair of first-half Navy touchdowns. Using their trademark spread option attack, the Midshipmen (7-3) churned out 190 rushing yards in the game's first 30 minutes.

By contrast, Notre Dame stumbled in the first half, gaining 159 total yards but never scoring.

Notre Dame struck first after the break and scored three times in the second half. But Navy had enough answers, and Notre Dame's red zone troubles caught up with them, as the Irish finished just 2-of-6 in opportunities inside the Midshipmen's 20-yard line.

"I'm not sure why we couldn't get them in the red zone," said Irish receiver Golden Tate, who had 132 yards and a touchdown. "That's definitely something we're going to be focused on working on next week."

Michael Floyd, back after missing five games with a broken collarbone, found immediate rhythm with Clausen and ended the day with 10 catches for 141 yards and a touchdown.

But his error also killed one of Notre Dame's most-promising drives.

Down 14 but moving in the fourth, Clausen threw to Floyd near the goal line, but the receiver had his back turned, attempting to lay a block. The pass bounced off Floyd's back and into the arms of Navy linebacker Ram Vela.

"He thought it was a screen (pass)," said Notre Dame coach Charlie Weis, who praised Floyd's overall effort. "He just missed a signal on the play."

With Notre Dame's BCS hopes now effectively dead, Weis' job security was again a topic of discussion after the game.

"It comes with the territory," Weis said of any added pressure. "It's not going to change my approach to how I coach."

Merrillville graduate and senior fullback James Aldridge saw no action Saturday.

COLLEGE FOOTBALL

Navy 23, No. 19 Notre Dame 21

Irish quarterback Jimmy Clausen threw for a career-high 452 yards.