The Cardinals will be without right tackle L.J. Shelton and linebacker Raynoch Thompson for at least their upcoming game against St. Louis.
Both Shelton, who might have torn left knee ligaments Sunday against San Francisco, and Thompson, who sprained his right shoulder in the same game, underwent magnetic resonance imaging tests Monday to determine the extent of the injuries.
Coach Dennis Green said Shelton’s status was unknown, other than he would miss a game.
Thompson said he expected to miss a game and then return for the final two games of the season. Shelton could miss the rest of the season, even if his ligaments aren’t torn.
Shelton’s spot in the starting lineup will be filled by Anthony Clement, who had been the starter before being replaced by Shelton nine games ago.
Green compared the mistake in the defensive backfield that allowed the 49ers a 19-yard completion on third-and-17 in overtime — keeping alive the game-winning drive — to another mistake in coverage in Carolina Nov. 21, when the Panthers completed a 28-yard touchdown pass with two seconds left in the first half.
“When you are playing zone, you have to have somebody underneath it and someone behind it,” Green said. “We had everybody behind it. It was just very poor spacing and just a real bad, probably the worst we had. . . as far as having a play where you had to make a play and having guys just not respond.”
Green said Josh McCown will remain as the starting quarterback this week.. . .
Since 1954, the only NFL team to post two wins in a year, with both over the same team, was the 1981 Baltimore Colts (2-14), who beat the New England Patriots the first and last weeks of the season. The 49ers, who beat Arizona twice, would be the second team if they lose their final three games.