Cardinals running back Andre Ellington runs some sprints to the side during practice Monday.

Coach Bruce Arians was unhappy with the work of his running backs at the Red and White practice on Saturday, so it was a welcome sight to see the return of starter Andre Ellington to the field on Monday.

Ellington put on pads for the first time since Week 13 of last season, and while his practice participation was limited with his hamstring still less than 100 percent, he's on the comeback trail.

"I wanted to get out there with my teammates," Ellington said. "Those guys are working hard every day

and I'm kind of missing out. I just want to make sure I'm ready before I get back out there (full-speed) so I can stay out there with them."

While it will ultimately be up to the trainers, Ellington was confident he will see action in the preseason opener on Saturday against the Chiefs.

"Is there a game Saturday?" Ellington said. "I'm there, and I'm playing."

Ellington, David Johnson and Marion Grice have all been sidelined since near the start of training camp with hamstring injuries, which has given the other four running backs on the roster – Kerwynn Williams, Stepfan Taylor, Robert Hughes and Paul Lasike -- plenty of work. While Arians has been complimentary of them at times, he was disappointed with their lack of production on Saturday, especially in live-tackling situations.

Arians said he will sit down with General Manager Steve Keim on Monday night and decide if they want to add another running back to the fold.

"We'll search and see what's available," Arians said. "I'm just not pleased with what we have right now at that position."

Johnson was drafted in the third round to help shoulder the ball-carrying load, but he's been out since hurting his hamstring on a long run on August 2. He is "very iffy" to make his NFL debut on Saturday, Arians said, and the shortage at the position is why Ellington isn't surprised to hear the chatter of possibly bringing in another back.

"Our room is getting a little short with guys banged up," Ellington said. "We need as much help as we can get."

FELLS STEPPING UP

One player who has made the most of his opportunity is tight end Darren Fells. Troy Niklas (hamstring) and Jermaine Gresham (back) are doing individual drills in practice but not yet participating in 11-on-11

work, and a healthy Fells has staked his claim as one of the starting tight ends.

He overtook John Carlson as the starter down the stretch last season and continues to improve.

"He's doing really, really well, and it's going to be hard to beat him out," Arians said.

Fells, a former professional basketball player who transitioned to football in 2013, has had his confidence rise as he becomes better-equipped in his new sport. While catching the ball came more naturally at first, Fells has really found his calling in the blocking game.

"I'm a big guy," said Fells, who is listed at 6-foot-7 and 281 pounds. "I'm more of a tackle than a tight end when it comes to weight. I'm physical, and most people don't think that a basketball player can be a physical, blocking type of guy, so I've been taking that blocking role to heart."

MATHIEU, PETERSON MAKING PLAYS

In what Cardinals fans hope is a sign of things to come for the defense – but not the offense – cornerback Patrick Peterson and safety Tyrann Mathieu intercepted quarterback Carson Palmer on back-to-back passes in 11-on-11 red zone work on Monday.

Mathieu had three interceptions in total during the practice, jumping a slant route during 1-on-1 drills against wideout Jaxon Shipley, and later leaping to pick off a Palmer pass headed for tight end Ifeanyi Momah in more 11-on-11 work.

POWERS HURTS OBLIQUE BUT LIKELY TO PLAY SATURDAY

Cornerback Jerraud Powers suffered an oblique injury on Saturday and left practice early, but pulling him was a precaution. While he didn't practice on Monday, Arians believes Powers will be ready for the preseason opener against Kansas City.

First-round pick D.J. Humphries (knee) and linebacker Sean Weatherspoon (hamstring) missed practice again but the hope is for them to return to Tuesday. Linebacker Shaq Riddick (hamstring), linebacker Darryl Sharpton (hip), cornerback Shaq Richardson (unknown), tackle Rob Crisp (knee), Grice (hamstring), cornerback Darren Woodard (groin), tackle Cameron Bradfield (unknown) and safety D.J. Campbell (hamstring) sat out.