OXNARD, Calif. (AP) -- In his preseason debut, George Selvie played as if he was an answer for the injury problems the Dallas Cowboys have had at defensive end.
In his second game, the fourth-year player looked more like someone who was out of a job when training camp started.
Selvie gets another preseason start Saturday at Arizona in what he figures might be his last good chance to make it in the NFL.
Tyrann Mathieu has been a camp sensation in his first shot with the Cardinals. The former LSU star will start at safety in place of the injured Rashad Johnson. The rookie sat out last season after the Tigers kicked him off the team over failed drug tests.
Mathieu had a 12-yard sack, a tackle for loss, a pass defended, two special teams tackles and a 24-yard punt return in his NFL debut last week, a 17-0 preseason victory at Green Bay.
Selvie wasn't quite that dominant a week earlier in the Hall of Fame game, a 24-20 Dallas victory against Miami.
But he had two sacks, made a great read on a bootleg to disrupt a play and forced Matt Moore to throw early when DeVonte Holloman returned an interception 75 yards for a touchdown.
"He looks like he has played in this league before," Cowboys coach Jason Garrett said. "He had a really good performance. But he's got to come back again and keep doing what he was doing."
That was a little more difficult when Selvie ended up running with the first team and faced starters five days later at Oakland. He didn't record a tackle - although he didn't get as many plays because of his move up the depth chart.
The Cowboys signed Selvie three days into camp after backup Tyrone Crawford tore an Achilles tendon in the first full practice and Anthony Spencer, the starter at left end in the new four-man front, was forced to miss the rest of camp for arthroscopic surgery on his left knee.
Selvie was working behind Brandon Bass, an undrafted player in his second year, until his play against the Dolphins.
"You've got to produce," Selvie said. "If you don't produce, I might be sitting at home again and know that I might not get another call."
Selvie was a seventh-round pick by St. Louis in 2010 out of South Florida, where he had nearly 70 tackles for loss and 29 sacks in four seasons. He played in all 16 games as a rookie for the Rams, but was among the final cuts a year later.
Since then, he's appeared in 20 games while bouncing from Carolina to Jacksonville and then Tampa Bay, which cut him before he could get on the field.
"The last few years have been a roller coaster ride," the 26-year-old Selvie said. "I think you grow and you learn. I think I'm a better player. I didn't want to be just a camp body. I'm not a camp body player, so I've got to go out there and show them what I've got."
Mathieu, a Heisman Trophy finalist in his second season with LSU in 2011, was a first-round talent who dropped to the third round.
The 21-year-old was mostly a cornerback and special teams star with the Tigers, but safety has been the 5-foot-9, 186-pound Mathieu's predominant spot in camp with the Cardinals.
"You just go out and make plays," Mathieu said. "I don't think there's any science to it. Physical characteristics will play its part in certain situations but for the most part, it's all about making plays and being in the right spot at the right time."