When Lewis looked around the Atlanta Falcons’ locker room on Thursday, his 350-pound mentor was just a distant memory.

"They tell me it’s part of the business," said Lewis, a rookie from Washburn University in Topeka, Kan. "All I know is that he helped a lot in learning how to play the position and how to read the offensive line and the other teams’ formations."

The Falcons are off this weekend, but it’s unclear how the break will affect their defense. First-year coach Bobby Petrino declined to speak with reporters after practice on Thursday, one day after Pro Bowl cornerback DeAngelo Hall strongly criticized the team for releasing Jackson.

Hall, who was fined $100,000 last month for confronting Petrino on the sideline of a Week 2 loss to Carolina, also refused interview requests.

Despite a 1-6 record and no victories in four tries against the NFC, the Falcons surprisingly released Jackson on Tuesday.

The move gave Lewis a starting job, but the sixth-round draft pick knows it will be tough to compensate for the loss of Jackson, who led the NFL with 13 tackles for lost yardage in 2006.

In seven games this year, Jackson had 21 tackles, 5.5 for minus-yardage.

Lewis will make his third start when the Falcons host San Francisco next week. Petrino and defensive coordinator Mike Zimmer have liked what they’ve seen this year from Lewis, who started this year when "3-technique" tackles Rod Coleman and Jonathan Babineaux were injured and couldn’t play.

"Yeah, I guess a turning point came in preseason," Lewis said. "The coaches liked what they saw, I guess, but the difference for me was watching those games on film and seeing how I reacted, how I used my feet and how I got my arms in the right position."

Despite ranking 13th in the NFC with an average of 126 yards rushing allowed, Atlanta currently has nobody listed behind Lewis at nose tackle.

Jackson, an 11-year veteran, was the Falcons’ best interior run-stopper.

The only consistent production on the line comes from right end John Abraham, a three-time Pro Bowl selection who has seven of the team’s nine sacks.

Coleman has played in just two games after undergoing quadriceps surgery this summer and injuring his knee in an attempt to return to the field sooner than expected.

Atlanta has been unable to compensate without Coleman, whose 44.5 sacks over the last four years led the NFL.

Another problem is at left end. Rookie Jamaal Anderson, a first-round pick from Arkansas, still doesn’t have a sack. The 21-year-old Anderson has arguably made just one big play, a forced fumble at Tennessee.

Anderson’s predecessor, Patrick Kerney, already has 3.5 sacks for Seattle. The Falcons let Kerney leave as a free agent even though his 58 career sacks ranked third in team history.

Chauncey Davis, the backup for Abraham and Anderson, would like a chance to start, but the former Florida State standout wonders if he’s being labeled permanently as a role player.

"I’m doing the same thing they asked me to do the first two years, be a reserve," Davis said. "We just have to keep on pushing and trying to get better. It’s like with Grady, there’s no sense in pouting about it, because that’s going to bring him back and it’s not going to help us improve."