Sam Houston State entered the weekend as the top-scoring team in the FCS.
It managed only one touchdown against a game Cal Poly squad Saturday, but it was still enough to squeek out an 18-16 win in the second round of the FCS playoffs.
The Bearkats (9-3), who reached the national championship game last season, will face the Stony Brook-Montana State winner in the quarterfinals next weekend.
Coach Willie Fritz's Southland Conference co-champions had averaged nearly 44.6 points per game in the regular season.
Against Cal Poly (9-3), the Bearkats' Miguel Antonio kicked field goals of 20, 32 and 26 yards, and Vincent Dotson blocked a punt out of the end zone for a safety to open the scoring.
Keshawn Hill scored Sam Houston's only touchdown on an 18-yard pass from Brian Bell with 31 seconds left in the third quarter, which gave the Bearkats a 15-6 lead.
Ryan Taylor's 50-yard touchdown pass to Willie Tucker with 1:34 to play pulled Cal Poly within 18-16, but Sam Houston's Trey Diller recovered an onside kick attempt and the Bearkats ran out the clock.
Bearkats junior running back Timothy Flanders rushed 17 times for 101 yards.
Bobby Zalud kicked three field goals for the Mustangs, from 23, 27 and 48 yards.
Cal Poly's triple option rushed for 224 yards, but leading rusher Deonte Williams managed only 48 yards on 13 carries.