Games against Division I-AA teams - like the one BYU played three weeks ago against Eastern Illinois - count officially, but they prove nothing. Against real competition, the Cougars are winless this season.

BYU failed on its latest try, losing 31-10 to San Diego State before 41,680 Saturday night at Qualcomm Stadium. The Cougars dropped to 1-3, losing two consecutive conference games to effectively fall out of the Mountain West championship race.

Not they were ever in it to begin with.

One game after rolling up 614 yards, BYU left its offense at the hotel on Coronado Island. Quarterback John Beck, who passed for a career high 517 yards against Texas Christian, couldn't throw it in the ocean.

"There was a mixture of coverage and looks," Mendenhall said of Beck's woes. "The Aztecs did a nice job of keeping him off balance."

The junior played possibly his worst game at BYU, certainly over the last two years. Even as a freshman he played well enough to lead BYU to a win in the same venue.

But this time, sophomore Kevin O'Connell was clearly the better quarterback on the field. After starting the season with three losses, the Aztecs have won two consecutive games.

"I think it's just the confidence in the game plan," O'Connell said. "Once you are comfortable with the offense, it's easier to attack and try to find some holes in the defense."

As bad as BYU's offense looked in the first half, it was even worse in the third quarter. Receiving the ball to start the second half, the Cougars gained 26 yards before falling apart.

Without a defender near him, Beck fumbled the ball as he tried to throw a pass. The Aztecs promptly covered 32 yards in seven plays to go up 24-3.

Game over. Season to follow?

"I think it was just ourselves that stopped us," Beck said. "For me, I really feel like I did not play to the level I needed to. We should have scored more, that's for sure."

The Cougars did get a measure of respect in the fourth quarter, scoring off an 11-play, 61-yard drive. Beck found tight end Jonny Harline for 35 yards on fourth-and-9 to overcome 20 yards of penalties on center Lance Reynolds for an illegal snap and unsportsmanlike conduct on the same play.

After Fahi Tahi's 2-yard touchdown run, BYU's defense gave up two big plays - one of which was Lynell Hamilton's 53-yard run - to allow the Aztecs to take a 31-10 lead. They needed only two minutes to go 90 yards.

BYU gained a 100 yards of total offense in the first half. Beck completed nine of 22 passes for 90 yards, including 25 yards on a possession in which SDSU's defense was guarding against the deep ball in the first half's closing seconds.

Beck's throws were often behind the intended receiver or over his head. On BYU's last possession of the first half, Marcus Demps intercepted a pass that was several yards over Zac Collie's head.

The Aztecs held BYU to 2-for-8 on third-down conversions in the first half. In SDSU's 52-21 win last week, San Jose State was 0-for-17 on third downs.

"We are finally understanding what position everyone is going to be in and trusting one another," said strong safety Reggie Grigsby. "If I take the chance to try and make a big play I know someone will be there to back me up. It is one of those deals where we got punched in the mouth a little bit in the first two games, but we are coming together."

Of course, BYU's offense in the first half could have made any defense look good. On three consecutive drives the Cougars did not manage a first down before punting.

A SDSU turnover contributed mightily to BYU's only score in the first half. Michael Franklin fumbled a punt, which Bryan Kehl recovered at SDSU's 40-yard line.

On third-and-4, Tahi took Beck's short pass over the middle and rumbled 27 yards. Even then, BYU's offense went backward.

On first-and-goal from the 7-yard line, Beck rolled out and was dumped for a 9-yard loss by Kurt Kahui. The next two passes weren't close to completions.

Jared McLaughlin came on to kick a 33-yard field goal.

Taking over on BYU's 24-yard line with 2:47 left in the second half, the Aztecs stormed down the field in 15 plays to score a touchdown. O'Connell had the drive's key play on a 21-yard quarterback draw.

"They're based in four wide receivers a majority of the time, but what's interesting is they're running the quarterback, running him effectively and running him often," Mendenhall said. "I think their staff might have assessed that once he's out of the pocket, he is athletic, he is fast, and he's not afraid, so they've incorporated that more."

O'Connell hooked up with Jeff Webb, who has caught a pass in 26 consecutive games, on a 14-yard reception to give SDSU a first-and-goal at BYU's 3-yard line. Hamilton scored on a 1-yard run with 37 seconds left in the half.

After Breyon Jones had a 33-yard kick return, Beck padded his statistics with three consecutive dump passes on Tahi.

"I don't think we were good enough on offense, defense and special teams," Mendenhall said.

San Diego State 31, BYU 10

IN SHORT: BYU had not lost to the Aztecs in San Diego since a 27-15 loss in 1988. Saturday's game marked the first time BYU has not scored in every quarter against San Diego State since losing 16-15 in 2000.

KEY STAT: The Aztecs finally got their running game untracked, amassing 265 yards on the ground, led by Lynell Hamilton with 161 yards, passing the century mark for the first time this year.

KEY MOMENT: Trailing 10-3 in the second quarter after a Jared McLaughlin field goal, BYU could not stop the Aztecs on their ensuing possession. Lynell Hamilton scored in the final two minutes from 1-yard out to take the wind out of BYU's sails.