Drew Bledsoe, Terry Glenn and the rest of the Cowboys` offense put this one to bed early. Bledsoe and Glenn followed Monday`s nearly flawless performance in Shreveport with another brilliant first half here at Texas Stadium, guiding the Cowboys to a 17-point halftime lead in an eventual 17-7 win over the San Francisco 49ers. Glenn made a leaping 28-yard touchdown grab late in the first quarter - his third of the preseason - and caught a 52-yard pass from Bledsoe in the second quarter which led to a Marion Barber touchdown run. Bledsoe finished 12-of-17 for 200 yards and was relieved by Tony Romo at halftime. Julius Jones had 15 carries for 56 yards and Barber rushed nine times for 49 yards. The Cowboys` first-team defense also remained stingy for the third consecutive game. In the second quarter, Cowboys cornerback Anthony Henry picked off Alex Smith`s deep pass intended for former Cowboys receiver Antonio Bryant. The 49ers finally got on the board in the third quarter when Smith hit rookie tight end Vernon Davis for a 15-yard touchdown. By then, the Cowboys had brought in their second-team defense. Romo drove the offense into 49ers territory early in the fourth quarter, but his pass bounced off tight end Tony Curtis` hands and was intercepted by Mark Roman. Shaun Suisham kicked a 25-yard field goal on the opening drive to give Dallas an early 3-0 lead, but he missed a 35-yard attempt at the end of the half. Veteran Mike Vanderjagt, who has been bothered by a sore groin throughout preseason, did not attempt a kick. Wide receiver Terrance Copper started in place of Terrell Owens (hamstring) and rookie Pat McQuistan started for Flozell Adams (calf). Marc Colombo started at right tackle for the second consecutive game, as did rookie free safety Pat Watkins. Larry Allen, a former 10-time Pro Bowl guard for the Cowboys, started at right guard for San Francisco wearing No. 71 in honor of his late Cowboys teammate Mark Tuinei.