Aaron Smith

PITTSBURGH — The Pittsburgh Steelers' loss at New England keeps getting worse.

Aaron Smith, one of the Steelers' best defensive players, is out for the rest of the season after he tore a biceps muscle during the 21-point loss to the Patriots on Sunday.

Smith, a defensive end, is an excellent run defender and one of the Steelers' most reliable players since breaking into the NFL as a fourth-round draft pick in 1999. He tried to keep playing during the 34-13 loss, but had to be replaced several times.

Coach Mike Tomlin knew that was a bad sign, and postgame tests revealed the tear. Smith apparently was not hurt on a specific play, but may have gone into the game with a partial tear that became worse as he played.

"Being the guy he is, he continued on," Tomlin said Tuesday. "He came out a few times, and that was worrisome because this guy doesn't come out of games."

Smith is used infrequently as a pass rusher in the Steelers' blitz-heavy defense, which didn't sack Patriots quarterback Tom Brady. The 31-year-old Smith does have a fumble recovery and an interception this season, and his ability to control offensive linemen regularly leads to sacks by the Steelers' linebackers.

Smith missed most of three games with a knee injury earlier this season and was replaced by Nick Eason. Travis Kirschke is also expected to get more playing time with Smith out.

The injury is not expected to be career threatening, Tomlin said. Smith was placed on injured reserve, a move that means he cannot return this season. Defensive lineman Ryan McBean was promoted to the 53-man roster.

McBean, a fourth-round draft pick from Oklahoma State, was released during the final preseason cuts and has spent the season on the practice squad.

"You're saddened for Aaron because he's a quality person and a quality player and he loves playing the game," Tomlin said.

Despite being outscored 17-0 in the second half by New England, the Steelers (9-4) still have a clear path to the AFC North title. They lead the Browns (8-5) by one game with three to play and, because they swept the season series with Cleveland, their lead is effectively two games.

The Steelers could clinch the division as early as Sunday when they play Jacksonville (9-4) at home and the Browns play the Bills (7-6) in Cleveland.

However, Sunday's loss may have ended the Steelers' chances of overtaking Indianapolis and being the second seed in the AFC playoffs, a spot that guarantees a week off and at least one home playoff game.

Now, even if they're seeded third, the Steelers would have to win a wild-card game at home, then, very likely, would have to win at Indianapolis (11-2) and New England (13-0) on successive weekends to reach the Super Bowl.