Not only do Pittsburgh stars Sidney Crosby and Kris Letang remain out with concussion-like symptoms, but both Michalek brothers - Penguins defenseman Zbynek and Senators winger Milan - are dealing with similar issues.
Zbynek Michalek hopes to return after missing the last seven games, but his younger brother will likely sit out a second straight contest since colliding with teammate Erik Karlsson in Buffalo on Tuesday. Milan Michalek had been enjoying a career season, leading the NHL with 19 goals at the time of his injury.
"Hopefully it's not too serious and he's going to be back soon," Zbynek Michalek said about Milan. "He's having a good season, so it would be a shame for him to miss a lot of time."
The Penguins can certainly relate to being without key contributors for long stretches. Crosby had 12 points in eight games - including three assists Nov. 25 in a 6-3 win over Ottawa - after returning from a nearly 11-month absence, but he's missed the last three contests with a recurrence of symptoms.
Letang, the standout defenseman who has 19 points in 22 games, hasn't played since Nov. 26, when he took a hit that earned Montreal's Max Pacioretty a three-game suspension.
"You just don't know if a guy is going to be one week, two weeks, or out longer," Penguins coach Dan Bylsma said about dealing with concussions. "That uncertainty makes it tough to plan in terms of down the road."
Pittsburgh (17-10-4) has managed to play well with a depleted roster for the better part of a year, but it may finally be starting to feel the effects. Bylsma's club has dropped three of four, slipping to third place in the Atlantic Division.
Evgeni Malkin gave the Penguins an early lead Tuesday against Detroit, but the Red Wings stormed back for a 4-1 win.
"We're not worried about the way we're playing, we just need to be a little bit more consistent and put some wins together," forward James Neal said.
The team could use more help from Jordan Staal, who has been dealing with a lower-body injury and has no points in his last six games.
The Penguins are expected to start Brent Johnson on Friday, perhaps because the No. 2 goalie has gone 8-1-1 with a 1.99 goals-against average against Ottawa. Marc-Andre Fleury, who has allowed three or more goals in eight of his last nine starts, is 7-8-1 with a 3.60 GAA in the series.
The Senators (14-14-4) have far bigger problems in net. Craig Anderson, signed to a four-year contract extension in March, fell to 2-4-1 this month after stopping 24 of 29 shots in a 5-2 loss to Boston on Wednesday.
Anderson's 3.42 GAA ranks in the bottom five among qualifiers, while Brian Elliott - traded away by Ottawa for Anderson in February - leads the league in that category.
They had 49 shots on goal against the Bruins after posting 44 the previous night in a 3-2 win over the Sabres, but went 0 for 9 on the power play in those games.
"If we continue to generate that kind of shots on goal, the puck is going to go in," coach Paul MacLean said.