Hali, who is facing a one-game suspension for violating the NFL's substance abuse policy, has led the Chiefs in sacks since 2008. His absence will force the Chiefs to scramble to find new ways to put pressure on QB Matt Ryan and the Falcons offense.
Here's how it will affect the outcome of this game.
While avoiding overconfidence, Matt Ryan knows that his job got a little easier. He won't have to deal with Hali chasing him around.
Hali's biggest strength is his ability to make quarterbacks get rid of the ball sooner than they would prefer. Ryan will now have that additional second or two to make an extra read and come away with the right pass to help the Falcons advance the football.
In his first game back to Arrowhead Stadium since being traded away, Tony Gonzalez could be Ryan's best friend in this game.
Hali can be limited when an offensive tackle and a tight end team up on him. With Gonzalez's blocking ability, the Falcons would have used him to keep Hali away from Ryan.
Now that Hali is out, head coach and defensive coordinator Romeo Crennel will need to get his players to figure out how to match up against Gonzalez. Chiefs fans know very well that Gonzalez is difficult to defend one-on-one and is more than capable of getting open and pulling in the big catch.
Tyson Clabo, far right, and Sam Baker, second from the right, enter the field with the rest of the starting offensive linemen.
Along with Ryan, offensive tackles Sam Baker and Tyson Clabo are pleased that they don't have to deal with Hali in this game.
They can now shift their attention to outside linebackers Justin Houston, Cameron Sheffield and Andy Studebaker. Crennel will be studying tape on these tackles, looking for ways that his linebackers can put pressure on Ryan.
During his rookie season, Justin Houston stepped up late in the season after a quiet first half of the year.
Houston, who was taken in the third round by the Chiefs, had 5.5 sacks in the final five games of the season. His ability to help Hali rush the passer was beneficial and helped the Chiefs post a few low-scoring victories in the latter portion of the season.
Now, Houston finds himself working without Hali for one game. But Houston learned a lot from Hali and hopes to assume his leadership role to help the Chiefs surprise the Falcons' offense.
Sheffield and Studebaker know they have big shoes to fill. But will the two of them working together be enough to step in for Hali?
Studebaker, who has mostly been effective as a special-teams player, came away with a pair of interceptions against the Pittsburgh Steelers when having to start for Mike Vrabel in 2009. Studebaker has played a little defensively, while Sheffield has had little to no defensive experience since being drafted in 2010.
The biggest question is, can one of them, or both, catch the Falcons by surprise and give Ryan a run for his money?