HOUSTON (AP) Kyle Postma had only seen the field late games as a quarterback over the last month and before that, it was at wide receiver.
The sophomore delivered when No. 16 Houston needed him most.
Postma, who came in for injured starter Greg Ward Jr. just before halftime, rushed for the go-ahead score and threw for another to rally Houston from 20 points down to a 35-34 win over No. 25 Memphis on Saturday night.
''It's indescribable,'' said Postma, who was with Houston as a redshirt freshman in 2013 before going to Trinity Valley Community College in Texas last season. ''I can't put this into words. It is crazy going out there and playing for my brothers and making plays out there on the field.''
His 7-yard touchdown run with 1:27 left capped a nine-play, 77-yard drive to give undefeated Houston the lead. Jake Elliott missed a 48-yard field goal wide right with 19 seconds left, sealing the win for Houston.
Houston first-year coach Tom Herman said he knew Postma had it in him.
''Gutsy. He's a pretty unflappable kid,'' Herman said. ''We talk about unit pride and competitive focus. Competitive focus meaning that when your number is called, you are prepared. When your number is called, you won't let your brothers down. I don't think anyone batted an eye when we put him in the game.''
With the Tigers (8-2, 4-2 American, No. 21 CFP) ahead 20-0, Ward left with what appeared to be a left ankle injury. Memphis had sacked Ward five times, and he hobbled off the field with 1:21 left in the first half after being sacked by Wynton McManis.
In came Postma, who tossed a 30-yard score to Linell Bonner with 37 seconds left in the half to cut the lead to 20-7. Postma ended up 21 of 33 for 236 yards and carried six times for 49 yards.
DeMarcus Ayers had 13 catches for 127 yards, and Kenneth Farrow had 10 carries for 46 yards and two touchdowns for Houston (10-0, 6-0, No. 24 CFP).
The victory puts Houston one step closer to its goal of winning the conference championship.
''We don't care,'' Herman said of the rankings. ''We don't talk about them. They matter none to us. We know that if we win our conference championship game, we are going to play in a New Year's Day bowl game. Our goal was not to be 10-0 after 10 weeks.''
Paxton Lynch was 20-of-31 passing for 278 yards and two touchdowns for Memphis, which lost for the second week in a row. Alan Cross caught a TD pass of 38 yards and Doroland Dorceus grabbed another for 61, both in the second quarter. Lynch also rushed for 43 yards.
''There are a lot of plays in the game that ultimately determine the outcome,'' Memphis coach Justin Fuente said. ''It wasn't the last play, and it wasn't first play. There was just a bunch. Both teams were out there battling, competing. We came up a little short.''
With 12:56 remaining, Farrow punched it in from 10 yards out to cut the Tigers' lead to 34-21.
Houston had a chance to narrow the gap following a Memphis fumble, but the Cougars had a touchdown negated by offsetting penalties, and Postma overthrew his receiver on fourth down from the 6.
Following a Lynch interception, Javin Webb cut the lead to 34-28 on a 1-yard touchdown run with 5:49 left. After a Memphis three-and-out, Postma led the drive to give the Cougars the lead.
Elliott had made field goals of 41 and 30 yards in the first half before missing in the final seconds.
Dorceus had 116 yards on 26 carries with a 6-yard touchdown run halfway through the third quarter. Tevin Jones also had a 25-yard TD run to give the Tigers a 34-14 lead to start the fourth quarter.
Farrow had sliced the Memphis lead to 20-14 with a 7-yard touchdown run in the third quarter.
Houston did not get a first down until five minutes to go in the first quarter. The Tigers outgained the Cougars 273-99 yards in the first half.
Houston had 11 rushes for minus 13 yards as a team in the first half. The Cougars finished with 96 rushing yards.
Texans' JJ Watt and DeAndre Hopkins, former major league pitcher Roger Clemens, who spent three seasons with the Astros and pitched for the Texas Longhorns, and Houston rapper Bun B were a part of a record crowd of 42,159 at TDECU Stadium.