ESPN College Football

FORT WORTH, Texas (AP) -- Robert Merrill took off to the right, stutter-stepped through a small gap in a wall of defenders and found an open lane to the end zone.

TCU was going to be just fine without its top two running backs and starting quarterback.

With that nifty 18-yard touchdown run in the second quarter, Merrill put the No. 20 Horned Frogs ahead to stay in a 30-14 victory over Vanderbilt on Saturday night.

Merrill, a freshman who didn't have a carry in the first two games, ran 29 times for 119 yards -- all after starting tailback Lonta Hobbs left the game midway through the first quarter with an injured right foot. Merrill also caught three passes for 44 yards.

"I was kind of nervous at the first, but once I got more carries and familiar with game speed again, everything worked out fine," said Merrill, whose last carries had been in the 2001 Texas Class 5A high school championship game when he ran for more than 200 yards.

Merrill's TD, which came on the first play after a Vanderbilt fumble, put the Horned Frogs (3-0) ahead 17-14.

Vanderbilt (1-3), which had all four of its turnovers in the first half, hasn't beaten a Top 25 team since a 27-25 win over No. 17 Georgia in 1991.

The Horned Frogs started the game without quarterback Tye Gunn (separated right shoulder) and backup tailback Ricky Madison (torn knee ligament).

Brandon Hassell, a fourth-year junior who had never thrown a pass in a game, overcame three fumbles (one lost) and an interception in the first quarter of his first start. He completed 15 of 30 passes for 227 yards, including a 17-yard TD to Quentily Harmon with 4:31 left in the game.

"It was definitely a rough start," Hassell said. "I made a lot of mistakes, but I just settled down and tried to move forward."

Hassell ran the first-team offense all spring while Gunn recovered from knee surgery. He had extra time to get ready with last week's open date after Gunn separated his shoulder in practice Sept. 9. The sophomore, 6-0 as TCU's starter, is expected to miss at least two more games.

Hobbs scored the first TD and ran for 40 yards on five carries, but landed awkwardly after being tackled on a 4-yard run and didn't return. Frogs coach Gary Patterson wouldn't discuss the injury, but Hobbs was on the sideline after halftime leaning on crutches with his foot in some kind of brace.

Merrill, who ran for 2,891 yards and 39 TDs as a senior at San Antonio's Taft High School, made the most of his chance.

"We watched him in the spring. He showed us that he could play," Hassell said. "He's got great moves. It's exciting to watch a guy like that play."

On the drive before Merrill's touchdown, TCU gained 88 yards on 20 plays but had to settle for Nick Browne's 22-yard field goal after Hassell lost a yard on a third-and-goal keeper from the 3.

Browne added field goals of 35 and 50 yards in the second half.

Hassell completed a 27-yard pass on his first play of the game, but fumbled twice the three plays after that for minus-16 yards and TCU punted.

The Frogs got the ball back when Marvin Godbolt picked off a pass -- his third straight game with an interception -- that deflected off receiver Brandon Smith. An illegal block wiped out Godbolt's 21-yard TD return, but Hobbs scored on a 7-yard run.

Vanderbilt's Jay Cutler threw his second interception, but Hassell gave the ball right back when he threw a pass behind his receiver that was picked off by defensive end Jovan Haye and returned 10 yards.

The Commodores tied it at 7 on the next play when Kwane Doster took a pitch, found a gap to the right and ran untouched 27 yards.

After TCU moved from its own 10 to the Vanderbilt 31 on just three plays, with the help of a personal foul penalty, Hassell made a great fake and then ran for 12 yards before fumbling after being hit by Haye.

"Hassell did a really good job with the option and the bootleg plays that they ran," said Vanderbilt coach BobbyJohnson. "He's a very slippery athlete. The TCU coaches developed a very good game plan for him."

Early in the second quarter, after another Vanderbilt fumble, TCU got to the 35 before an incomplete pass on fourth-and-3.

Vanderbilt needed just three plays to go 65 yards for a 14-7 lead when Cutler threw a 43-yard TD pass. Smith, who wrestled the ball away from a defender for an 18-yard gain on the first play, streaked past two Frogs and was wide open when he caught the TD pass in stride at the goal line.

Cutler finished 17-of-36 for 250 yards.