SANTA CLARA -- Anthony Dixon knows how tough it will be to stick on the 49ers roster for a third straight year.

Dixon is among a surplus of running backs behind starter Frank Gore. That group could see casualties when the first wave of roster cuts comes Monday, a day after the 49ers play their third exhibition game against the host Denver Broncos.

A strong showing Sunday could help Dixon (a) make sure he's not among those initial 14 players released to reach the 75-man limit, (b) enhance his chances of making the 53-man roster Aug. 31 and (c) help his video résumé for other potential suitors.

"They've made more competition in the room," Dixon said of the 49ers backfield options. "When you see that, you've got to step up your game. I'd be crazy not to.

"It's made me better, though."

Dixon's tenure became endangered upon the offseason arrivals of Brandon Jacobs, a seven-year veteran from the New York Giants, and LaMichael James, a second-round draft pick.

Although Jacobs suffered a knee injury Saturday in Houston, that hasn't given Dixon an edge to become the short-yardage specialist. Coach Jim Harbaugh said Thursday that Jacobs already has shown enough to merit a regular-season role.

Dixon, meanwhile, "can't wait" for the season to start.

A 2010 sixth-round draft pick from Mississippi State, Dixon spent all offseason at the 49ers' facility, working hard for precisely the situation that surfaced in Saturday's game.

Summoned for a fourth-and-1 carry, Dixon found enough room for a 2-yard gain on the busted play. How did he find it?

"They kind of had us outnumbered there," offensive coordinator Greg Roman said of the Texans. "Anthony basically was his own blocker to get us that first down."

Said Dixon: "I was pushing my feet. I've got to give credit to the countless hours of sled pushes during the summer. Shout out to the sled pushing."

Four plays later, however, Dixon couldn't push through for another fourth-and-1 conversion.

Dixon finished with five carries for 12 yards, including a 9-yard run. He also avoided, in his words, "mental busts" that plagued him in the exhibition opener, such as running out of bounds while the 49ers' tried to kill the final minutes.

Roman came away impressed with the "physicality" of Dixon's encore in Houston, noting: "Anthony had one of his best games since I've been here. ... He needs to have another great one this week."

Dixon knows he didn't have a great final week to last season. In the fourth quarter of the NFC Championship game, the got stopped for no gain on a third-and-1 run at the Giants' 46-yard line.

After an offseason agonizing over that play, he's on the run again. "I still have work to do."

  • The 49ers are the first NFL team to join the "It Gets Better" video project to condemn anti-gay bullying. Four defensive players took part in the one-minute video: Ahmad Brooks, Ricky Jean Francois, Isaac Sopoaga and Donte Whitner.

    "The San Francisco 49ers are proud to join ItGetsBetter.org, to let all LGBT teens know that it gets better," Whitner said in the video. "On behalf of the entire 49ers organization, we are on your side, and we promise it gets better."

  • Players were given Friday off before traveling Saturday to Denver.

    For more on the 49ers, see Cam Inman's Hot Read blog at blogs.mercurynews.com/49ers. Follow him on Twitter at twitter.com/CamInman.

    Sunday's game

    49ers (1-1) at Denver (1-1), 1 p.m. FOX