Wilson cut it to 3-1 during a 4-on-4 at 5:19 of the third, tapping in a pass from Evgeny Kuznetsov, and Ovechkin scored on a one-timer from the left circle on a power play at 13:18 to pull the Capitals to within 3-2.
Strome then tied it 3-3 with a backhand into an empty net with DeSmith down in his crease at 17:16.
"It's a tough one," Capitals forward T.J. Oshie said. "It just wasn't a good enough 60 minutes against a good hockey team over there. Odds were stacked against us a little bit tonight, and we weren't able to find our game until maybe a little too late."
Poehling put the Penguins ahead 1-0 at 10:10 of the second period. He took a stretch pass from Danton Heinen before skating past Rasmus Sandin and scoring top shelf with a wrist shot on a partial breakaway.
"I think tonight it was just a weird game," Poehling said. "We ended up getting a win. Coming down the stretch, these games are hard. You can't make mistakes."
Ruhwedel made it 2-0 at 12:17 with a snap shot glove side from the right circle. It was his first goal since April 23, 2022 (45 games).
Guentzel extended the lead to 3-0 on a power play 27 seconds into the third period, shooting five-hole with a wrist shot on a breakaway.
"It was an emotionally charged game," Penguins coach Mike Sullivan said. "There were moments in the game where I thought we were really good. There were moments in the game, not so much. I think the most important thing is, especially this time of year, that we walked away with two points."
NOTES: Malkin scored his 81st game-winning goal in the NHL, tying Boston Bruins forward Patrice Bergeron for the fifth among active players. … Ovechkin is one goal away from becoming the first player in NHL history with 300 power-play goals. … Capitals forward Sonny Milano did not play and is out at least one week with an upper-body injury. … Penguins goalie Tristan Jarry backed up DeSmith after being unavailable because of a lower-body injury for a 3-2 loss to the Dallas Stars on Thursday.