The multitude of do-rights who follow Brigham Young University football rarely plunk down on their seats at Cougar Stadium until quarterback Robbie Bosco has had time to warm up his arm and throw a quick touchdown or two. For the most part, the hollering isn't pretentious, and nobody gets drunk.

Some of the 65,383 may have thought about tearing down the goal posts this afternoon after the Cougars' stunning 28-21 upset of No. 4 Air Force, but life by Mormon Standard Time prohibits such behavior. After BYU rallied and scored 21 unanswered points in the second half to overcome the Falcons' 21-7 halftime lead, a few moms and dads ran out to hug their sons, the cheerleaders cried and performed an obligatory routine or two, and little kids threw snowballs.

"This was a classic football game," BYU Coach LaVell Edwards said when it was over. "I told the team that I have never been more proud of a comeback than today's."

Representatives of 10 bowls watched the game from the press box, including agents for the Cotton, Sugar and Orange bowls. In victory, No. 16 BYU raised its record to 9-2 and remained in the running for a 10th consecutive Western Athletic Conference title. Had Air Force won, the Falcons would have assured themselves of at least a tie for the conference championship, and they would have hung on to the nation's longest winning streak. That mark ended at 13, exactly 13 games since Air Force last played BYU, and lost, 30-25, in Colorado Springs. The Falcons' record is 10-1.

Said Fisher DeBerry, the Air Force coach, "I thought the physical size of BYU's team made a big difference. We are not anywhere in their mold. I don't care what LaVell says."

To win, BYU came out in the second half and shut down a sleepy Air Force offense, the same offense that had been so dominant in the early going. Vai Sikahema, who stands only 5 feet 8 and weighs 186 pounds, gets credit for single-handedly swinging the momentum BYU's way. He returned a punt 72 yards after Air Force was shut down on its first possession of the third quarter. Then, after Bosco had moved the team 74 yards and made it 21-21 on a 25-yard touchdown pass to Mark Bellini, Sikahema found himself thrust into the lights again when Bosco went to him for the game-winning score.

From his halfback position, Sikahema slipped behind the coverage of all-America linebacker Terry Maki, took in Bosco's wobbly lob and ran 69 yards for the touchdown with 5:41 left in the game.

Air Force threatened to tie it on its last drive, as Bart Weiss moved the offense down to BYU's eight. The final effort started at the Falcons' 17 and ended as time expired when Weiss threw a desperate pass to Marc Munafo that was intecepted by BYU's Rob Ledenko in the end zone.

"We were tight in the beginning," Edwards said, "but never intimidated. I don't think we were as patient as we needed to be, but we came through when it counted there at the last. And that's what matters."

The BYU receivers, facing a stingy Falcons defensive secondary, were frustrated throughout the first half, but no more so than Bosco, who fought hard from the outset but was never able to get his big-bang, air-it-out offense in high gear. For the day, Bosco completed 29 of 49 passing attempts for 343 yards, but he spent the early afternoon running round and round, trying to save his hide from the Falcons' rush. He was sacked four times and threw three of his four interceptions in the first half, all of which resulted in Air Force touchdowns, two on returns by cornerbacks Tom Rotello and Dwan Wilson.

His first monumental blunder came on the third play of the game, when he underthrew Bellini and the ball went into the hands of Pat Malackowski at the BYU 40. On the ensuing drive, the Air Force wishbone was at its finest, as Weiss worked the corners of the front line off a triple-threat option. To score, Weiss faked the fullback dive, then threw to halfback Randy Jones, floating just beyond coverage, for the 21-yard touchdown.

It was something to consider that here was Bosco, one of the nation's top quarterbacks -- a strong Heisman Trophy contender, who was leading the nation in passing offense with an average 367.9 yards a game -- performing like a comic bungler. His first pass on the Cougars' second possession was blocked. And his second attempt sailed way off the mark and landed in the hands of Rotello, who returned the ball 25 yards to give the Falcons a 14-0 start. The score came only 20 seconds after Air Force had finessed its first score, and there were little more than 12 minutes left in the first quarter.

In the first half, Air Force overwhelmed the Cougars on both sides of the ball. But after completing only two of 12 passes in the first quarter, Bosco finally found his rhythm and moved the team 70 yards to score with 12:46 left in the half. The touchdown came when he threw 22 yards to Bellini, who had worked a good two steps behind safety Scott Thomas on the post pattern, and enabled the Cougars to at least look competitive.

That glory was short-lived, however. The next time BYU got the ball, Bosco was intercepted by Wilson on the Air Force 42. On the return, Wilson charged past a few potential tacklers at midfield, then found a clear lane along the sideline, and it was this route he used to cover most of the ground on his 58-yard touchdown run. The Cougars led, 21-7, with 8:36 left in the half.

With the enormous potential of BYU's offense, however, the Falcons knew better than to get overconfident. Coaches love to say every game calls upon a savior to make the big play and turn things their way. The BYU surge came with the emergence of Vai Sikahema as hero, and Robbie Bosco playing like Robbie Bosco again.