PITTSBURGH (AP) The defensive void left by injured inside linebacker Ryan Shazier is so considerable that two players will fill it for the Pittsburgh Steelers.

Coach Mike Tomlin confirmed Friday that Shazier's shoulder injury that knocked him from the game during the fourth quarter last week will keep him out of Pittsburgh's road game at St. Louis (1-1) on Sunday.

''We have some capable guys, and it's the next-man-up attitude here,'' linebacker Lawrence Timmons said. ''We've got Vince Williams, and we've got (Sean) Spence. More than capable guys.''

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Shazier, the Steelers' first-round pick last year, had a 15-tackle performance last week against the 49ers. Shazier had 11 solo tackles, one dazzling 17-yard sack, three stops behind the line, a quarterback hurry, a forced fumble and a fumble recovery. Shazier's 22 tackles through two games are fourth best in the NFL.

He left last Sunday's win late with a stinger, something he described as a ''linebacker injury.'' It prevented him from practicing all week, forcing Shazier to miss the eighth game of his young career.

''The key to our defense is for everyone to do their job,'' Spence said. ''That's just what Ryan did last week. He did his job and made the plays that came to him, and I feel as a defense if we continue to do that we all can have those kinds of games.''

Shazier was expected to be a full-time starter as a rookie, but foot and knee injuries limited him to half a season. Williams and Spence benefited from his absence by getting key reps. Williams primarily played in passing situations, while Spence was the run stopper next to veteran Timmons.

''The confidence is definitely there,'' Williams said. ''I think the coaches believe in us, and we believe in ourselves. It's not something that we haven't done before. We both have starting experience, so we're both ready to go.''

Spence started nine games and played in all 16 last season after missing two years with a severe knee injury sustained during the 2012 preseason, his rookie year. Williams, a third-year player, has 13 career NFL starts, including 11 as a rookie in 2013. Despite their experience, Spence and Williams will be hard-pressed to replace Shazier's production.

''He's a special athlete (with) a lot of speed out there, a lot of energy,'' Timmons said. ''He's going to be missed, that's for sure. But we have capable guys come in and do the job and hold on until he gets back and gets healthy. . But I just hope that he comes back fast, because we need him. He's one of our best players right now, and we need him.''

Notes: The Steelers also will be without second-year nose tackle Daniel McCullers (knee), while CB Cortez Allen (knee) is questionable against the Rams. CB William Gay (not injury related), DE Cam Heyward (elbow) and WR Markus Wheaton (chest) are probable.

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AP NFL website: www.pro32.ap.org and www.twitter.com/AP-NFL

Ryan Shazier's breakout game came with a familiar price.

The second-year Pittsburgh Steelers linebacker will sit out Sunday's trip to St. Louis with a shoulder injury. Vince Williams and Sean Spence will fill in for Shazier.

Shazier injured the shoulder in the fourth quarter of last week's romp over San Francisco. Shazier led the Steelers with 15 tackles, including a sack and a fumble recovery. He called his shoulder issue ''a linebacker injury,'' but it prevented him from practicing all week. Shazier missed seven games in 2014 with knee and ankle problems.

While Shazier is out, nose tackle Daniel McCullers and cornerback Cortez Allen are questionable.

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AP NFL website: www.pro32.ap.org and www.twitter.com/AP-NFL