Abraham, the NFL's active sacks leader, made it through just 15 snaps in last week's divisional playoff victory over Seattle before aggravating a left ankle injury that forced him to leave in the second quarter.
"You don't want to lose a good player," Falcons defensive coordinator Mike Nolan said. "We won the game, so there's something we did right. But it does change things."
The Falcons are making contingency plans in case Abraham is unable to play at full strength against the San Francisco 49ers on Sunday at the Georgia Dome.
Abraham, who has not been available to speak with reporters this week, missed practice on Wednesday even though coach Mike Smith listed him as having limited participation.
But it's clear that the Falcons (14-3) will be pleased to have Abraham on the field for any length of time against San Francisco (12-4-1).
"He's a sack master," linebacker Sean Weatherspoon said. "That's what I like to call him - Father Abe. We look forward to getting him back out there this week. I think the guys that had a chance to play in his absence did a good job stepping in and doing what they need to do in order to help the team get the win."
Abraham, 34, was initially hurt in the regular season finale loss to Tampa Bay, limping off the field with the help of trainers.
Coach Mike Smith said that he expects the 13th-year veteran to start on Sunday. Even so, the Falcons are giving reserve ends Cliff Matthews, Jonathan Massaquoi and Lawrence Sidbury more work this week in case Abraham has to make an early exit.
Matthews took the balance of the work against Seattle, playing 46 snaps and making two tackles opposite Kroy Biermann, Atlanta's other starting end.
Abraham, though, is a special talent.
"Obviously he's an integral part of this defense," Biermann said. "When you lose a player like that, it kind of puts a little bit of strain on you, but the guys behind him know that they've got to step up, play that role and get it done."
The 49ers present several problems for Atlanta's defense.
Quarterback Colin Kaepernick is coming off an impressive playoff win over Green Bay, passing for 263 yards and two touchdowns and rushing for 181 yards and two TDs. He set an NFL single-game record for yards rushing by a quarterback.
Smith knows the Falcons must do their best to contain Kaepernick in the pocket while keeping tight coverage on receivers Michael Crabtree and Randy Moss and tight ends Vernon Davis and Delanie Walker.
Running backs Frank Gore and LaMichael James also create issues in the passing attack, too.
"They have playmakers at both levels with their offense," Smith said. "You're going to have to put together a plan to try to slow down certain aspects of it. It's a very explosive offense they've created."
Though Abraham's 122 career sacks rank 13th on the NFL career list, he hasn't had one since Nov. 29 when he took down New Orleans quarterback Drew Brees to help seal a 23-13 victory.
The following week, Atlanta won its second NFC South title in three years.
Before the Falcons traded for him in 2006, Abraham had a long injury history in six years with the New York Jets. He's overcome assorted ailments and offseason surgeries with Atlanta, however, and has missed just two games over the last six seasons.
"When you watch the film, he played through the pain a little bit," strong safety William Moore said. "It was hard to even tell. He rotates a lot, so I didn't even know he was out at one point."
Moore learned of Abraham's absence soon enough while Seattle quarterback Russell Wilson and the Seahawks were carving up Atlanta's defense in the second half. After Vance Walker sacked him early in the third quarter, Wilson completed 13 of 18 passes for 230 with two TDs.
The Falcons did a decent job covering deep routes, but they struggled badly in trying to defend tight end Zach Miller and other targets Wilson hit in the middle of the defense.
"Those were still miscues on our end," free safety Thomas DeCoud said. "We were short on a drop here or there or someone didn't carry someone here or there. Those things were more about us rather than things that they did."
Notes: S William Moore has a cast on his right hand but participated fully in practice. ... CB Christopher Owens (hamstring) remains out. He hasn't played since a Dec. 22 victory at Detroit. ... DT Jonathan Babineaux (shoulder) also had limited participation in practice.
John Abraham
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