TEMPE, Ariz. (AP) Arizona's dynamic running back Andre Ellington missed practice Friday with a foot injury.
The Cardinals did not reveal the severity of the injury or whether it would keep him out of Monday night's season opener against San Diego.
Ellington, a crucial part of the Cardinals' plans, was hurt in practice Thursday.
Coach Bruce 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.''
Backup running back Jonathan 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.''
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, who topped 1,000 yards in combined rushing and receiving as a rookie last year.
''That's out of my pay scale,'' Goodwin said. ''I don't talk about injuries.''
Arians had limited Ellington's participation in preseason games to minimize the chance of injury.
A sixth-round draft pick out of Clemson, Ellington quickly emerged as a big-play threat as last season progressed.
He rushed 118 times for 652 yards and caught 39 passes for 371 yards, becoming the first Cardinals rookie to top 1,000 yards from scrimmage since Anquan Boldin in 2003.
Ellington's average of 5.5 yards per carry was the highest of any back in the NFL with a minimum 100 carries.
This year, he learned all the wide receiver positions and figured to be a frequent target of quarterback Carson Palmer to make the best use of his abilities in the open field.
In Ellington's absence, the lead running back role falls to Dwyer, a free agent signee in the offseason.
Dwyer, whose biggest strength may be his pass blocking, has 971 yards rushing and 176 yards receiving in four NFL seasons, all with the Pittsburgh Steelers. He has a career average of 4.2 yards per carry.
In 2012, Dwyer played in 13 games, including the only six starts in place of the injured Rashard Mendenhall.
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.''
None of them, though, comes close to Ellington's game-breaking ability.
Ellington's biggest game thus far came against Atlanta, when he rushed for 154 yards in 15 carries, including an 80-yard touchdown run,
Against Tennessee he rushed for 71 yards in 10 attempts - a 7.1 average per carry - and caught four passes for 87 yards - 21.8 yards per catch. He was the ninth player since 1960, and the only rookie, to top 7 yards per carry (minimum 10 attempts) and 20 yards per reception (minimum four catches) in a game.
With that performance, Ellington joined Hall of Famer Ollie Matson as the only players in Cardinals history to have at least 70 yards rushing and 80 yards receiving. They were the Chicago Cardinals when Matson did it in 1952.
AP NFL website: www.pro32.ap.org and www.twitter.com/AP-NFL