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 post-game 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.

"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.

The Steelers swept three road playoff games en route to winning the Super Bowl two years ago, but this team is 2-4 on the road with three losses in its last four road games.

Not that Tomlin is ready to begin speculating about the playoffs and postseason seeding, especially with Jacksonville up next and a road game against St. Louis (3-10) following four days after that.

"I live week to week, I really do," Tomlin said. "I don't feel great about where we are, I seek perfection like everyone else, but I don't feel bad, either. We live in the moment and we prepare for the next opportunity to play."

The next opportunity to play the Patriots, perhaps?

Patriots coach Bill Belichick didn't make a new friend in Tomlin with his postgame comments about Steelers safety Anthony Smith, who was beaten twice in coverage for touchdowns. Smith's ill-advised guarantee of a Steelers win in Foxborough became a motivational tool for New England and the source for some derisive comments by Belichick.

Belichick suggested Smith was targeted because "the safety play at that position was pretty inviting." He also said the Patriots have "played against a lot better safeties than him."

Tomlin was displeased with Smith's pregame remarks, but he also didn't like another coach critiquing his players.

"I don't care what coach Belichick has to say after a game regarding our performance," Tomlin said. "I compliment them on a great game and we move forward. ... Do we need to play better? Absolutely. But it won't be because he said it."

Copyright 2007 by The Associated Press. All Rights Reserved