ARLINGTON, Texas -- Dallas Cowboys quarterback Dak Prescott said last week he is ready for the regular-season opener against the New York Giants. He showed Saturday that he wasn’t kidding.

Prescott completed 11 of 14 passes for 113 yards and a 10-yard touchdown pass to TE Jason Witten in the Cowboys' 24-20 preseason win against the Oakland Raiders.

Prescott's numbers would have been better if not for two penalties on the offensive line that wiped out first-down completions to receivers Cole Beasley and Terrance Williams. Prescott connected six times with Witten for 74 yards, including a 28-yarder down the seam.

In two preseason games, Prescott has thrown for 219 yards and two touchdowns on 18-of-22 passing.

Since starters don't play in the final preseason game, the next time he'll be on the field will be against the Giants.

QB depth chart: The Cowboys are serious about making Cooper Rush their No. 2 behind Prescott, even if Rush is an undrafted free agent. Rush threw two fourth-quarter touchdown passes -- 7 yards to Ronnie Hillman and 44 yards to Lance Lenoir. In four preseason games, Rush has six touchdown passes and no interceptions. Perhaps most impressive on Saturday was his ability to come back from his lost third-quarter fumble, which the Raiders returned 65 yards for a touchdown. In four preseason games, Rush has completed 38 of 51 passes for 398 yards with six touchdowns and no interceptions.

When it was starters vs. starters, the Cowboys looked...: At times good and at times shaky. The good was the offense scoring on its first two drives. The shaky was a secondary that was beaten for touchdowns of 17 yards and 48 yards. There appeared to be a miscommunication on Raiders receiver Cordarrelle Patterson's touchdown, and Cowboys safety Byron Jones took a poor angle on receiver Amari Cooper's 48-yarder. The secondary was a big question entering the summer and remains one, especially if the Cowboys can't generate a consistent pass rush.

One reason to be concerned: The linebacker position might take a huge hit if Anthony Hitchens' right knee injury is serious. He went out with 19 seconds left in the second quarter and did not return. Hitchens is the starting middle linebacker but can also play the weakside. While many have high expectations for Jaylon Smith, he would not start over Hitchens, who was credited with more than 100 tackles last season. Damien Wilson could face a suspension for an offseason arrest, and Smith is working back from a major knee injury. What looked to be a strength for the defense could now be a big-time question.

That guy can't start: The Cowboys have given Chaz Green every chance to earn the left guard spot this summer. He hasn't been able to stay healthy, which has been the story of his young career. He started off OK at left guard, but then allowed a sack. He moved to left tackle on the Cowboys' final series of the first half and suffered an ankle injury. As much as the Cowboys want Green to be the guy, they just can't rely on him to stay healthy. The left guard spot could be Jonathan Cooper's by default.

In and out: RB Ezekiel Elliott got 14 snaps in last year's preseason. This year he has played 10. He ran six times for 18 yards and caught two passes for 6 yards on the first drive before his night ended. The Cowboys were not going to put him at risk of injury and wanted to give him a taste of action. This might be his only game action until October because of his six-game suspension. He has an appeal hearing Tuesday in New York and will not take part in practice on Monday or Tuesday.

Good work: Sean Lee played 15 snaps in his longest work of the preseason, which is about what the weakside linebacker needed to get ready for the regular season. Lee was credited with three tackles, but he missed a tackle that led to a long run by Raiders RB DeAndre Washington. If Hitchens is out, Lee's value to the defense increases even more, if that is possible.

Rookie watch: Cowboys DE Taco Charlton picked up his second sack in four preseason games when he dropped QB EJ Manuel for a loss in the third quarter. The best part of Charlton's play was his celebration. He appeared to make tacos for his teammates, who gladly consumed them.

Keep the hands close: La'el Collins had been making a smooth transition to right tackle this summer after playing left guard his first two seasons, but he had three penalties (two accepted) in the second quarter. The two illegal-use-of-hands penalties wiped out first-down catches by Beasley and Williams on back-to-back drives.