Backup quarterback Tanner Mangum threw a 42-yard Hail Mary touchdown pass to Mitch Mathews on the game's final play as BYU stunned Nebraska 33-28 on Saturday at Memorial Stadium in Lincoln, Neb.

The Cougars played their final four series with Mangum after starting quarterback Taysom Hill left the game with a foot injury. The victory ruined the debut of Cornhuskers coach Mike Riley and was Nebraska's first season-opening loss since 1985, the longest such streak in the nation.

Mangum completed 7-of-12 passes for 111 yards and engineered the final drive that began at the BYU 27-yard line with 48 seconds remaining.

Hill, coming off a season-ending leg injury five games into last season, threw for 268 yards and ran for 72 before departing in the second half. After the game, coach Bronco Mendenhall announced that Hill will miss the rest of the season with a Lisfranc fracture in his foot.

Cornhuskers quarterback Tommy Armstrong threw for 318 yards and three touchdowns, including a 9-yard touchdown pass to tight end Trey Foster with 5:31 remaining in the third quarter that gave Nebraska a 28-24 lead.

Trevor Sampson's 35-yard field goal pulled the Cougars within 28-27 with 7:57 remaining, and BYU began their game-winning drive after Cornhuskers sophomore kicker Drew Brown missed his second field goal attempt of the game.

The Cougars led 24-14 at halftime, converting an Armstrong fumble deep in Nebraska territory into a touchdown after the Cornhuskers had leads of 7-0 and 14-7.