Andre Ellington uncertain for Arizona

— -- TEMPE, Ariz. -- Cardinals running back Andre Ellington was not at Friday's practice, a day after undergoing an MRI for a foot injury.

With just three days until Arizona opens its season on "Monday Night Football," Ellington's status for the season opener remains iffy. He was listed as limited because of his foot on the Cardinals' first injury report of the season Thursday, but it was released after coach Bruce Arians met with reporters.

A source tells ESPN's Chris Mortensen that Ellington was to be examined by a local foot specialist on Friday.

Arians did not talk to reporters Friday and offensive coordinator Harold Goodwin was less than forthcoming.

"Who knows what's going to happen?" Goodwin said. "We'll see who's out there on Monday. Next man up, that's our philosophy."

If Ellington can't play Monday, Jonathan Dwyer would start in his place. Last season as a backup with the Pittsburgh Steelers, he had 197 yards on 49 carries. Starting six of 13 games in 2012, Dwyer had 623 yards on 156 carries.

Dwyer acknowledged Ellington's injury.

"It's unfortunate that our brother is injured right now, but we know he'll be back," Dwyer said. "We don't know when."

As a rookie, Ellington rushed for 652 yards on 118 carries and finished with 1,023 total yards from scrimmage. His average of 5.53 yards per carry led the NFL.

The lack of information stems from the Arizona coaching staff's desire to keep the Chargers guessing as to whether they would have to deal with Ellington.

"That's out of my pay scale," Goodwin said. "I don't talk about injuries.

Second-year back Stepfan Taylor and journeyman Robert Hughes are the team's other two running backs.

"We all can play," Dwyer said. "We all can make big plays. I know we're going to get more opportunities, and we're going to take advantage of them."

Information from the Associated Press was used in this report.