Chris Johnson out: Cardinals could be in for rough ride

TEMPE, Ariz. -- Although the Arizona Cardinals are cruising along with a five-game winning streak, the ride could get rough real soon.

The Sports Xchange confirmed Monday that running back Chris Johnson fractured a tibia.

Although Jay Glazer of FOX Sports reports Johnson will miss "extended time," the team will not confirm that nor guess at how long he might be out and Johnson still seems in denial, telling some that he expects to play.

However, with co-starter Andre Ellington also hobbled, this probably means rookie David Johnson will start Sunday at St. Louis. The Cardinals are expected to promote Kerwinn Williams from the practice squad.

As of Monday morning, Johnson was listed as the starter ahead of Ellington on Arizona's depth chart, but the two split time in the backfield -- when they are healthy.

Johnson, OKA (once known as) CJ2K after gaining 2,006 yards rushing in 2009, has 784 yards on 184 carries with three touchdowns this season.

David Johnson and Stepfan Taylor are the other running backs on the Cardinals' roster.

Meanwhile, there plenty more concerns on the roster.

Cornerback Jerraud Powers (calf) might not play Sunday and three defensive linemen did not play in last Sunday's win over the San Francisco 49ers -- Frostee Rucker and backups Cory Redding and Ed Stinson.

Given those injuries, the Cardinals are entering the most challenging part of the season. After playing the Rams on Sunday, they meet the Vikings at home on a Thursday night.

That game could mean the difference between playing at home or on the road at some point in the playoffs.

The Cardinals insist it's too soon to look to ponder what the playoff picture will look like in January.

"It's getting to that point in the season, we're having some injuries and guys are going to have to step up," said safety Tyrann Mathieu. "They are going to have to play big.

"There are a lot of ups and downs. It's December football. It's going to get tough."

The Cardinals yielded only 13 points to the 49ers, but the defense wasn't happy with the way it played.

That's why cornerback Patrick Peterson, a captain, called off victory Monday for the defense. An 11 a.m. meeting was scheduled to go over tape and discuss communications breakdowns.

"These next five games are very important," Peterson said. "If we want to be home for playoff games, we have to make sure we win them. Minnesota is playing good ball. Although Green Bay lost, they're playing good ball.

"We have to play those guys eventually, so we have to make sure we win those games. We have to start out fast and have good energy so we can give ourselves a good chance to win."

REPORT CARD VS. 49ers

PASSING OFFENSE: C -- Quarterback Carson Palmer was sacked only once, but he took several hits. He wasn't as sharp as usual, but the 49ers did a good job in coverage, too. It was the first game this season in which Palmer did not throw a touchdown pass.

RUSHING OFFENSE: D -- Only 70 yards on 29 carries. The Cardinals ran the ball eight times with no more than three yards to gain for a first down. They lost yards five times, gained nothing twice and scored on a one-yard run. The 49ers' defensive line dominated the line of scrimmage vs. the run.

PASS DEFENSE: C -- The Cardinals knew quarterback Blaine Gabbert would use a lot of bootlegs and other misdirection. But they didn't do a great job of handling it. Gabbert passed for 318 yards and a touchdown.

RUSH DEFENSE: B -- Playing with a depleted defensive line, the Cardinals did a decent job. The 49ers gained 67 yards on 17 carries. The Cardinals are giving up too many rushing yards in the red zone.

SPECIAL TEAMS: C -- Kicker Chandler Catanzaro missed his third extra point of the season. He has missed more extra points than field goals, also three. Punter Drew Butler put two into the end zone. The Cardinals did recover a muffed punt.

COACHING: C -- The Cardinals were mentally prepared to play a losing team. But they didn't play well. They blocked poorly in short yardage situations and there were communications problems on defense.