FORT WORTH, Texas (AP) -- Aaron Brown was again the only one of TCU's top three tailbacks dressed to play. He came through with another impressive performance.

Brown ran for 73 yards and two touchdowns, taking option pitches to the right and to the left for scores, and caught five passes for 59 yards as the No. 23 Horned Frogs beat I-AA UC Davis 46-13 on Saturday night for their 12th straight victory -- the nation's longest I-A streak.

"We just try to give him the ball as much as we can, and he has a chance to break plays," said Jeff Ballard, undefeated as TCU's starting quarterback. "He's a special player. It's a comfort zone for me with him in the game."

Senior running backs Robert Merrill (back) and Lonta Hobbs (foot), both who have had 1,000-yard seasons, haven't played in either game for TCU (2-0). Brown has made sure they haven't been missed too much.

"I'm trying to be versatile and keep defenses off key so they don't know if I'm going to run or catch," said Brown, who finished with 132 total yards.

Brown had 156 total yards in the season-opening 17-7 victory at Baylor, the sophomore's first career start. He ran 15 times for 49 yards and caught four passes for 107 yards, including the go-ahead 84-yard TD in that game.

Ballard was 18-of-23 passing for 190 yards with two touchdowns and ran for another score in his three quarters against UC Davis. He has been the starter in the last 10 TCU wins since replacing injured senior Tye Gunn last season.

TCU has the longest winning streak because defending national champion Texas lost 24-7 to Ohio State on Saturday night. That was the Longhorns' first loss in 22 games.

"Any time you're first in the country, it's something special," Ballard said. "The longest streak, that's exciting for us. We hope to extend on that."

That may not be easy with No. 24 Texas Tech coming to Fort Worth next week. TCU lost 70-35 to its in-state rival two years ago.

UC Davis (1-1), which won 20-17 at Stanford last season, got a field goal on its opening drive in its first game ever against a Top 25 team. But TCU scored on its next four possessions to go ahead 23-3 and finished with 461 total yards.

"We watched them on film, but when you get on the field, their speed is a little different. I really thought, the stats might not show it, our defense played well," Aggies coach Bob Biggs said. "Our defense was on the field a long time, and they started to beat us on the edge."

Jon Grant was 13-of-25 passing for 211 yards with two interceptions and scored the Aggies' only touchdown on a disputed leaping dive into the end zone.

The Aggies are completing the transition from Division II to I-AA and have had 36 straight winning seasons. TCU coach Gary Patterson was the linebackers coach at UC Davis in 1986.

Ballard ran for TCU's first score, lunging into the end zone after a UC Davis defender swiped at his ankles inside the 5. That came two plays after Walter Bryant made a leaping, one-handed catch across the middle of the field.

TCU had short fields for its next three drives, starting at the UC Davis 36 after a muffed punt snap and twice at the 32. The Frogs got a 49-yard field goal from Peter LoCoco, an 18-yard TD pass from Ballard to Shae Reagan and Brown's first score.

Marvin White's interception set up the TD for Brown, who had a 16-yard catch and 12-yard run on the short drive before scoring.

"We played to our potential tonight," Brown said. "We don't look past anybody."

The Frogs learned that lesson the hard way in the second game last season.

After being unranked and opening 2005 with a 17-10 upset victory at No. 7 Oklahoma, the Frogs lost to overmatched SMU the following week. They haven't lost since.

"This week in practice, we had a lot more focus, a lot more attention to detail. We were not going to let that happen again," Ballard said. "SMU was a fluke thing that shouldn't have happened. UC Davis was another team like them, that could sneak up on us."

Grant scored just before halftime on a keeper, leaping inside the 5 and extending the ball. While in the air, he was undercut by Jared Retkofsky and didn't appear to get the ball over the goal line. But the referee ruled touchdown. With no indisputable evidence to overturn the call, the touchdown stood after a review.