Ottawa (7-6-1) opened the season with a 1-4-1 stretch that saw the club play without defenseman Filip Kuba (broken leg), while center Jason Spezza (groin) and goaltender Pascal Leclaire (groin) also missed time.
The Senators have won six of eight since that sluggish start, and Kuba and Leclaire are expected to return soon. However, Ottawa has picked up more injuries along the way with Spezza re-aggravating his groin and Michalek hurting his knee.
Spezza, with nine points in nine games, is the only member of the injured to return thus far.
"We've gone through a lot of adversity as far as injuries are concerned and, to me, that's a credit to the players," coach Cory Clouston told the team's official website. "The guys have handled it and dealt with it very, very well. To me, that's going to give us some positive outcomes as the season goes along."
Ottawa turned in another strong performance Saturday despite the injuries, winning 3-2 at Montreal behind two goals from Alex Kovalev.
Michalak is likely to play for the first time since Oct. 28, when he had a goal and an assist in a 5-3 victory over Florida. The left wing is tied for third on the team with four goals.
He has one goal and five assists in his last five meetings with Atlanta (6-5-3).
Brian Elliott will likely make an 11th consecutive start in place of Leclaire.
Elliott has won five of six games with a 2.33 goals-against average. He won his only home meeting with the Thrashers by making 26 saves in a 4-2 victory Oct. 10, 2009.
Kovalev has five goals in his last six games, moving the right wing within three points of 1,000 for his career.
"You know, you look back and you get to the NHL at 19 years old and now you're over 1,000 games and getting to 1,000 points," he said. "I mean, it's a long journey and a big achievement. I'm definitely proud of myself."
Kovalev struggled against Atlanta last season, totaling one point in four meetings -- three of them losses for Ottawa.
The Thrashers have dropped three of four after falling 5-4 in a shootout to Chicago on Saturday. Still, coach Craig Ramsay was encouraged by his team's effort.
"We battled, we chased, we skated, we really looked like our team again," Ramsay said. "We looked like we had speed and we put a lot of pressure on their defense."
AccuScore has powered more than 10,000 simulations for every NHL game on ESPN.com, calculating how each team's performance changes in response to game conditions and opponent's abilities. Each game is simulated and the game is replayed a minimum of 10,000 times to generate forecasted winning percentages.