TEMPE, Ariz. -- It doesn't matter to Chris Johnson whether he's the Arizona Cardinals' starter or backup at running back.
He's been preparing the same way this season since signing in mid-August. That mindset may just pay off Sunday in Chicago.
The Cardinals backup running back may start this week depending on how quickly Andre Ellington returns from the sprained right PCL he suffered in Sunday's win over New Orleans. If Ellington can't play against the Bears -- or longer -- Johnson will start in his place, coach Bruce Arians said.
And Johnson, who turns 30 on Sept. 23, said he'll be ready.
"I'm always preparing myself like I'm getting 20, 25 touches a game," Johnson said Monday at his locker.
"With me (my mindset ) don't change at all. Practice hard every week, study a lot, and just, even though when you're not the starter, you still have to go in there like you're going to have to play. They're still going to need you and knowing that I'm going to have a role on this team, I can't sit there and not prepare like a starter even though I'm not the starter. I got to prepare the same way."
Every backup in the NFL understands they're a snap away from becoming a starter, but Johnson, who's in his eighth season, feels that philosophy is more apt for running backs.
"That's always a possibility as a running back," Johnson said. "We get hit every single play. It's probably the most physical position on the team."
Since he missed the majority of training camp, Johnson is starting to feel the physical effects of getting hit that he would have normally experienced in early August. Because of his delayed training camp, Johnson doesn't feel like he's at full speed.
But Sunday against the Saints helped speed the process, he said. Prior to Ellington's injury with about 12 minutes left in the fourth quarter, Johnson had three carries for 7 yards. He tried staying loose when the defense was on the field in case he was needed. When Ellington left the game, Johnson took his place and had seven carries in the fourth quarter for 30 yards, which allowed him to try to find a "groove."
"It was kind of good for me to get in there in (the) fourth quarter and get some touches back-to-back and get a rhythm," Johnson said. "Anytime you are in there, even with a receiver, catching the ball, learning your offensive line, you need to get in a rhythm."
Arians felt Johnson looked "solid" despite missing one hole on a play he's not accustomed to yet.
Arians doesn't feel the offense will change much if Johnson takes Ellington's place. Ellington will have the option to practice Wednesday and if he can practice Friday, he'll likely play Sunday. If Ellington is sidelined Sunday, Johnson will likely have the running game to himself. Arians doesn't want to shoulder rookie running back David Johnson with the responsibility of an expanded role.
"In time," Arians said. "I don't want to put too much pressure or take rookies and give them too much piece of the pie too early. It's not healthy to put them in the situation too much."
While promoting Kerwynn Williams from the practice squad if Arizona has only three healthy running backs is a possibility, Arians said, he's also comfortable with traveling with three backs.
Arians wouldn't put a timetable on the injury but said Ellington could potentially miss one-to-three weeks, and in that time Chris could steal the starting job from Ellington. Not that it would matter much, Arians said.
"It will always be a one-two punch," Arians said. "Who will start? It doesn't matter to me who gets the carries."