Brassard remained at third-line center with left wing Conor Sheary and right wing Bryan Rust.
"It's not what we wanted, losing those two guys," Brassard said. "Losing a guy that scored almost 100 points this year and 40 goals, you can't really replace that, the way [Malkin] plays and everything. But as a group, we're all going to have to step up and play some big minutes, and try to play different roles."
Malkin, who led the Penguins with 42 goals and 98 points this season, temporarily left Game 5 of the first round after colliding with Flyers forward Jori Lehtera at 16:25 of the first period, resulting in Lehtera falling on Malkin's left leg. Malkin returned for the start of the second period and played 20:22 in a 4-2 loss.
In four regular-season games against the Capitals, Malkin had six points (two goals, four assists). He had seven points (three goals, four assists) in seven games during the second round against Washington in the 2017 Stanley Cup Playoffs.
Hagelin, a main component on the penalty kill, had three points (one goal, two assists) in six games against Philadelphia. Without Hagelin, Sheahan said Pittsburgh's penalty killers remain confident because they practice against the NHL's top power play from the regular season (26.2 percent).
"It's always a challenge when we do penalty kill in practice against these guys," Sheahan said. "It's a lot of fun and definitely helps you. You work on some things and you're kind of ready for anything because these guys are so skilled with the puck. So hopefully that'll translate and help us out."