MOBILE, Ala. _ Frontrunners for so long, San Diego State couldn't answer when it fell behind early on Saturday night against South Alabama.
The 19th-ranked Aztecs, heavily favored by 19 points, had not trailed in a game in more than 16 quarters dating back to last season. But it found itself down after the first drive, and the Aztecs seemed to be battling their way back in their first loss in 14 games.
Looking flat coming off a bye after a 3-0 start, SDSU didn't have an answer in a 42-24 defeat at Ladd-Peebles Stadium.
South Alabama (3-2) scored three fourth-quarter touchdowns and beat SDSU (3-1) for the second straight year.
Though SDSU led at halftime, the Jaguars scored on a 79-yard pass on the second play for the third quarter. SDSU answered to take lead again, but the Jaguars answered with a 20-yard scoring pass, a 1-yard TD run after a bad snap on a punt, and an 80-yard fumble return for a TD.
SDSU's D.J. Pumphrey notched 151 yards rushing to move to 20th on the NCAA's all-time yardage list, but SDSU managed only 313 yards as a team.
The Aztecs led 16-14 at halftime, but it took an interception and a last-minute drive to give them their first lead after trailing for all but five seconds of the first half.
SDSU cornerback Derek Babiash perfectly read the roll right of Garvin and stepped in front of his pass in the end zone for the first pick of his career.
That gave SDSU the ball with 1:50 left in the half, and the Aztecs overcame two sacks of Chapman, who had little time to throw in the first half and earlier fumbled the ball away. Receiver Eric Judge gained 27 yards when he came back for the ball, but the Aztecs ran out of time for anything more than the 34-yard field goal by John Baron II.
The total yardage for the first 30 minutes � USA with 179 and SDSU 168 � wasn't lopsided, but that wasn't what it looked like., USA sustained longer drives, running 15 more plays; had six more first downs; and the Jags held the ball for more than 21 minutes.
It seemed that the Jaguars, already a 19-point underdog, would be in big trouble with the loss of their starting quarterback Dallas Davis (turf toe) and top running back Xavier Johnson (ankle).
Garvin, ga Georgia high school product who sat out last season after transferring from Marshall, was playing his first live football since 2013, but he hardly looked intimidated or confused by SDSU's 3-3-5 defense.
In the first half, Garvin was sharp passing, completing 9 of 13 passes for 120 yards. He also presented a running wrinkle that would have been impossible for Davis had he played. Though Garvin was sacked three times in the first half � once blasted full-speed by linebacker Calvin Munson � he tucked the ball several times and ran for a total of 30 yards.
When SDSU roughed the punter after stopping USA on its first drive, Garvin hit receiver Josh Magee for a 31-yard completion, and running back Thomas Tyries took the next play to the end zone from 12 yards.
SDSU found itself down for the first time since the third quarter of its Mountain West championship game win over Air Force, and it looked like it might have trouble answering.
Three of SDSU's first four drives ended on three-and-outs, with Chapman not connecting on his first three passes. Pumphrey couldn't find holes, running for 2 yards on his first three carries.
The Aztecs solved that problem with two big plays: Mikah Holder made a great over-the-shoulder catch for 33-yards, and on the next play Rashaad Penny bounced outside, going untouched for a 15-yard score. SDSU still trailed, 7-6, when the extra point was botched.
USA answered on the next drive with trickery � a flea-flicker in which Garvin got the ball and threw to Kevin Kutchera, who beat SDSU's top corner, Damontae Kazee for a 37-yard score. USA led 14-6.
Pumphrey broke free on SDSU's first drive of the second quarter. After a 32-yard punt return by Quest Truxton gave SDSU the ball at the USA 40, Pumphrey busted through the middle for 36 yards, lost three on the next play and then fought his way through tacklers for a 7-yard score.
