With injuries wiping out three starters, including two on the offensive line, not much was expected out of the Cowboys’ first-team offense in Monday’s preseason opener with the Raiders.

And that’s a good thing because other than a 24-yard catch by Dez Bryant, the offense barely did anything in the first half at O.co Coliseum during a scoreless first half.

David Arkin, a guard who didn’t play a snap all last year as a rookie, started at center, a position he’s been practicing for only the last two weeks with starter Phil Costa (back) held out -- and with backups Kevin Kowalski (ankle) and Bill Nagy (ankle) out for the entire preseason, if not longer.

Arkin struggled at times in the middle, getting overpowered by bigger nose tackles, but he did handle his snaps to the quarterback well, both in shotgun and under center. Center exchanges have been an issue for most of the preseason.

The first-team offense had three possessions, totaling only 21 yards.

Defense steps up: While the offense struggled to move the ball in the first half, the Raiders weren’t that much better, thanks mostly to an aggressive Cowboys defense, especially in the secondary.

Playing without cornerbacks Morris Claiborne and Mike Jenkins, the secondary made a few plays, including an interception by safety Gerald Sensabaugh, who was able to play center field on a play that cornerback Orlando Scandrick had covered on a deep ball intended for Raiders WR Jacoby Ford.

Outside linebacker DeMarcus Ware was all over the field, making two tackles for no gain, and applied steady pressure in his limited snaps.

Rookie LB hurt: Fourth-round pick Kyle Wilber had to leave the field in the first half and get X-rays on his thumb. Wilber was expected to get plenty of snaps with the second-team defense.

The fourth-rounder from Wake Forest missed most of the offseason with a finger injury that required surgery.

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