Cardinals linebacker Lamar Louis Looks to make a tackle during the team's 38-17 win over Denver Thursday.

The fourth preseason game means little to many, as starters sit and fans wait for the beginning of the regular season.

But for someone like Lamar Louis, undrafted rookie linebacker, Thursday's night preseason finale against the Broncos at University of Phoenix Stadium meant everything.

"Going into it you're not getting many reps in the other preseason games, then you're expected to play full speed, special teams and defense," Louis said after the Cardinals' 38-17 win. "It's a huge deal for guys like me, fighting for a roster spot."

Coach Bruce Arians had estimated there were only about four roster spots left on the soon-to-be 53-man roster – final cuts, trimming 22 off the team, must be made Saturday by 1 p.m. – and the game, Arians said, made some decisions easy,

some more difficult.

It does not help that outside linebacker Kareem Martin suffered an MCL injury on his left knee, possibly sidelining him a few weeks and leaving a special teams hole that must be accounted for on that 53-man roster. It also didn't help that, with rookie cornerback Brandon Williams having his issues, fellow cornerback Cariel Brooks missed a tackle on a short pass that turned into a 57-yard touchdown for Broncos wideout Jordan Taylor, and then Brooks later allowed a second TD to Taylor that "was even worse," Arians said.

Arians was happy with his offensive and defensive lines, important since none of the starters on either side played. One player of note was Earl Watford, coming back from a knee injury, starting at left tackle and holding up over a couple of series. If Watford can play tackle – which Arians sounded like he believed so – the Cardinals may be able to keep one less offensive lineman on the roster.

"This week my main focus was to get back out there and give it one good test run before the actual season started," said Watford, who had never played left tackle in a game. "It felt good."

Wide receiver John Brown, who hadn't played all preseason because of a concussion, got on the field for a few plays as well, saying he felt fine.

The Cardinals (1-3) also salvaged a victory out of the preseason. And there were players who flashed.

Quarterback Matt Barkley played better, completing 20-of-29 passes for 262 yards and a pair of touchdowns. But it was the Cardinals' running game that dominated. Undrafted rookie running back Elijhaa Penny had 113 of the Cards' 170 rushing yards as he made his bid for a roster spot.

"(Running backs coach) Stump Mitchell kind of told me I was going to get the ball a little bit to show what I can do," Penny said.

"I'm pretty sure, if not the Cardinals, I impressed 31 other teams," he added.

Penny's problem is that he is new to special teams, Arians said, and that's the part of the game these final four spots require. The top three running backs – David Johnson, Chris Johnson, Andre Ellington – are set, and Arians noted fourth back Stepfan Taylor is "one of our core guys" on special teams.

That's not a problem for Louis, who has caught the coaches' collective eye in the transition game.

"His stock has really risen the last two weeks," Arians said. "He's one of those guys who might have played his way on the football team."

Louis is hoping so. He'll be waiting a couple of days to find out for sure.

"Mentally I'm pretty good," Louis said. "I gave it all I had. I think I can help this team, but like coach Arians said, you're auditioning for all 32 teams. I prayed up, and said, 'Lord, I'll give it all I have and let the chips fall where they fall.' I think I did pretty good."