San Francisco 49ers running back Kory Sheets, front, leans forward to score a touchdown against the defense of Dallas Cowboys cornerback DeAngelo Smith (31) and cornerback Mike Mickens, center, in the second half of a preseason NFL football game Saturday, Aug. 29, 2009, in Arlington, Texas. (AP Photo/LM Otero)

San Francisco 49ers linebacker Manny Lawson (99) wraps up Dallas Cowboys tight end Martellus Bennett following Bennett's reception in the second half of a preseason NFL football game Saturday, Aug. 29, 2009, in Arlington, Texas. (AP Photo/LM Otero)

Dallas Cowboys head coach Wade Phillips shouts instructions from the sideline during the second half of a preseason NFL football game against the San Francisco 49ers, Saturday, Aug. 29, 2009, in Arlington, Texas. (AP Photo/LM Otero)

San Francisco 49ers fullback Brit Miller, left, celebrates with running back Kory Sheets (30) following Sheets' touchdown in the second half of a preseason NFL football game against the Dallas Cowboys, Saturday, Aug. 29, 2009, in Arlington, Texas. The 49ers won 20-13. (AP Photo/Donna McWilliam)

San Francisco 49ers fullback Brit Miller (47) runs for extra yardage as Dallas Cowboys safety Pat Watkins (25) attempts to bring him down in the second half of a preseason NFL football game Saturday, Aug. 29, 2009, in Arlington, Texas. The 49ers won 20-13. (AP Photo/Donna McWilliam)

Dallas Cowboys tight end Martellus Bennett (80) is upended by San Francisco 49ers cornerback Tarell Brown, bottom, as linebacker Diyral Briggs, rear, assists on the tackle following Bennett's reception in the second half of a preseason NFL football game Saturday, Aug. 29, 2009, in Arlington, Texas. The 49ers won 20-13. (AP Photo/Donna McWilliam)

Dallas Cowboys quarterback Tony Romo looks downfield as San Francisco 49ers defensive end Justin Smith (94) rushes in the first half of a preseason NFL football game Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/Donna McWilliam)

Dallas Cowboys running back Felix Jones smiles after scoring a touch down against San Francisco 49ers safety Mark Roman (26) and San Francisco 49ers safety Dashon Goldson (38) in the first half of a preseason NFL football game Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/Donna McWilliam)

Dallas Cowboys wide receiver Miles Austin (19) is wrapped up by San Francisco 49ers cornerback Nate Clements, right, in the first half of a preseason NFL football game Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/Donna McWilliam)

Football fans cheer on at the start of a preseason NFL football game between the San Francisco 49ers and Dallas Cowboys, Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/Donna McWilliam)

Dallas Cowboys running back Marion Barber (24) runs past San Francisco 49ers defensive tackle Aubrayo Franklin (92) in the first half of a preseason NFL football game Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/Donna McWilliam)

Dallas Cowboys quarterback Tony Romo (9) reacts as running back Felix Jones scores in the first half of a preseason NFL football game against the San Francisco 49ers, Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/LM Otero)

Dallas Cowboys wide receiver Patrick Crayton (84) tries to break the tackles by San Francisco 49ers cornerback Nate Clements, rear, and linebacker Patrick Willis, right, in the first half of a preseason NFL football game Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/Donna McWilliam)

Dallas Cowboys quarterback Tony Romo, left, hands off to running back Marion Barber, right, in the first half of a preseason NFL football game Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/LM Otero)

San Francisco 49ers quarterback Shaun Hill, front, scrambles as defensive tackle Ricky Jean-Francois, right, blocks Dallas Cowboys defensive end Jason Hatcher, left rear, in the first half of a preseason NFL football game Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/LM Otero)

Dallas Cowboys wide receiver Kevin Ogletree, is tackled by San Francisco 49ers cornerback Nate Clements, center left, after making a reception as safety Mark Roman (26) and defensive end Justin Smith (94) look on in the first half of a preseason NFL football game Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/Tony Gutierrez)

Dallas Cowboys running back Felix Jones (28) is wrapped up by San Francisco 49ers cornerback Nate Clements, second from left, as he attempts to gain extra yardage on a run in the first half of a preseason NFL football game Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/Tony Gutierrez)

San Francisco 49ers running back Michael Robinson (24) is brought down by Dallas Cowboys linebacker Keith Brooking (51) in the first half of a preseason NFL football game Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/Tony Gutierrez)

Eddie Brixey, wearing mask, of Fort Worth, Texas, inflates a Dallas Cowboys helmet in the parking lot outside as he and others tailgate outside the team's new stadium before the start of a preseason NFL football game against the San Francisco 49ers, Saturday, Aug. 29, 2009, in Arlington, Texas. (AP Photo/Donna McWilliam)

Dallas Cowboys head coach Wade Phillips, left, and San Francisco 49ers head coach Mike Singletary chat on the field before the start of their preseason NFL football game, Saturday, Aug. 29, 2009 in Arlington, Texas. (AP Photo/LM Otero)

San Francisco 49ers head coach Mike Singletary, center, shouts instructions to his team in the second half of a preseason NFL football game against the Dallas Cowboys as running backs coach Tom Rathman, left rear, and quarterbacks coach Mike Johnson, right rear, look on, Saturday, Aug. 29, 2009, in Arlington, Texas. The 49ers won 20-13. (AP Photo/Donna McWilliam)

San Francisco 49ers running back Kory Sheets goes over the top of the pile to score a touchdown in the second half of a preseason NFL football game against the Dallas Cowboys, Saturday, Aug. 29, 2009 in Arlington, Texas. Cowboys linebacker Steve Octavien (53) and center Matt Spanos (78) are shown at front. (AP Photo/LM Otero)